This is how the ubiquity of the American flag in the US feels like to foreign visitors (and even to Americans). Even Americans can feel this way about Wearing a Flag on Your Head.
The fleur-de-lis symbol in Louisiana. It's especially noticeable in the stuff they sell in gift shops.
Texans love to emblazon things with the motif of the Texas flag, put Lone Stars on everything, and even produce things shaped like the state itself, right down to tortilla chips and Belgian waffles. Texans love Texas.
Canada is much the same way, putting maple leaves on anything.
On the same note, the province of Quebec, Canada absolutely loves their fleur de lys.
One criticism of conspiracy theories is that most of them seem to assume that the conspiracy is more concerned with scattering symbols that point to their existence than they are with actually controlling the world. And yet...
At Disney Theme Parks, even the manhole covers are emblazoned with the silhouette of Mickey Mouse's head. They're called "Hidden Mickeys" and are more of a Genius BonusRunning Gag, a way for designers to leave a subtle signature on their work — the majority of them are very well hidden. The pattern of large-oval-with-two-smaller-ovals shows up a lot. The electrical tower shown as the page image is one example. Whole books have been written on the topic!
EPCOT used to have a logo for each Future World pavillion plastered all over them. The last to keep its logo was Spaceship Earth (aka The Big Ball), though Innoventions still had its original CommuniCore logo as the carpet pattern in a hallway in the west building until May 2007. Now the logos show up as Easter eggs in newer rides and on certain limited-edition merchandise (i.e., a set of pins released to mark the park's 30th anniversary in 2012).
At Walt Disney World and Disneyland, Buzz Lightyear's Space Ranger Spin is a ride that involves riding through a course of space monsters, etc. and firing at them to score points. The only spots that register a hit are the very conspicuously placed Zerg symbols on each target.
Nazi Germany loved those hypnotic spinning swastikas so much they put them on just about everything the state had authority over. Even canned food.
And a forest; nobody seems to know precisely when it happened, or who was responsible, but someone planted a number of larch trees in the middle of a mostly-evergreen forest that formed a swastika when viewed from the air for a few weeks in autumn. The East German government either didn't notice or decided it wasn't worth the time and money to do anything about this, and it wasn't until the 1990s that the trees were cut down.
And now another even larger one has been noticed in Kyrgyzstan, suspected to be the work of German POWs trolling their Soviet captors.
Post war, during what the U.S. miltary called "Denazification," the symbol was purged from most buildings. Some structures just had to remove a statue — ranging from some that were blown up, to just the emblem being carved out, as seen on this building◊. The Olympic Stadium has some remaining that could not be removed.
In the USSR, stars and hammer-and-sickle symbols were absolutely everywhere. And you'll still see them in present-day Russia. Post-communist authorities initially made a great effort to remove them all, then eventually got tired and gave up.
Helped by three facts: a) sometimes it was darn expensive to remove the sigils, and spending the already scarce funds on cosmetic changes when everything goes straight to hell is not the best thing to do, b) virtually every culture- or government-related structure had various related symbols absolutely everywhere, sometimes with every single decoration being filled with them, upping the cost spectacularly, and c) some of the sigils were just plain too awesome to remove (e.g. the stars on the Moscow Kremlin towers, made from ruby glass and fitted with a complex lighting system). Thus, the ones you will get to see are usually the grandest or the most artful examples of Sigil Spam.
The Windows key appears on every (non-Macintosh) keyboard since ~1995. This tends to make Linux users not very happy, or most Windows users, for that matter.
Likewise, many 1980s microcomputers — such as Commodore's, Apple's, and Atari's — had similarly branded keys with various functions. Apple eventually replaced theirs with a symbol that looks like a cloverleaf. (The others just all stopped making computers.)
Apple introduced their symbol keys on the //e in 1982, the same year Atari dropped their symbol key starting with the 1200XL (replacing it with an "Inverse" key).
Apple replaced the logo by the "cloverleaf" symbol (actually called "point of interest" symbol) specifically to avert this trope: they didn't want the menus on the Macintosh to have Apple logos all over the place.
BlackBerry has a variant.
Cigarette ads in Indonesia, to a downright absurd degree. In most streets, you literally cannot look around without spotting at least a half dozen cigarette ads.
The government of American Samoa is actually required to put their official seal on nearly everything they own or make. This includes school buses, a memorial to an airshow accident, and doctor's notes from the government-run hospital.
You can throw a rock in Mexico at random and odds are it will hit an eagle-eating-a-snake crest.
Grant Morrison has referred to brands and logos (the McDonald's golden arches, Nike swoosh, Coca-Cola logo, etc.) as corporate viral sigils.
In recent years, it's become fashionable for car manufacturers to work a tiny version of the corporate/division logo into places like the reflector just ahead of the headlight bulb (Mk5 Golfs and Jettas have a VW roundel in that exact spot, 2008-up Chevy Malibus have a bowtie there AND in the rear side reflectors...)
The backdrops for a lot of press conferences can look this way.
The Pennsylvania Railroad, which at its height was the largest railroad in the world, put its keystone symbol over much of the northeastern parts of the USA. Not only did most engines, carriages, and wagons wear the Keystone, but the PRR also put its symbol on some of its bridges and all of its stations, some of which still stand.
The most lasting effect, however, is probably in the names of train stations: the main passenger rail terminals in New York City, Baltimore, Pittsburgh, and Newark are all named "Penn Station" (short for "Pennsylvania Station") after the railroad. Most—but not all—of these have the famous keystone in the architecture. (New York Penn Station in particular was completely demolished and rebuilt as a rather dingy, functional underground station in the late 1960s to make way for Madison Square Garden; there are currently plans to rebuild the whole thing and get rid of MSG, but it's unclear if the new station will have the keystone.)
The railroad's main center in Philadelphia also bore the name, but eventually dropped it on account of how locals all came to call it 30th Street Station. Ironically, the difference is because PRR was based there: 30th Street Station was built to replace Broad Street Station, which had gotten too small for PRR's gigantic traffic but wasn't demolished until long after 30th Street became operational, so "Pennsylvania Station" would have been supremely useless as a name, as there were two of them a whole mile apart from each other.
The Consolidated Rail Corporation (Conrail) was also notorious for doing this. It is justified because the railroad was originally a government plan to combine six bankrupt railroads all with separate attributes and systems of operation into one large, single, and uniform operation. Because of this, Conrail spent its first few years of operation modernizing its predecessors' property like signals, buildings, bridges, etc. Conrail's name, logo, and iconic blue and white color scheme is seen all over signs, buildings, and equipment and despite being bought out and disbanded in 1999, Conrail sigil is still seen today on various railroad property.
Most modern (20th century and newer) North American railroads with a discernible logo could be accused of this to some extent. Naturally, the larger ones do more of this than some 2-mile-one-locomotive shortline.
In Britain, the old British Rail symbol can still be found in most stations.
A recent surge in nationalism made it so that most local clothing shops now have some form of garment that bears the three-stars-and-a-sun motif of the Philippine Flag. There is even a clothing line called exactly that that sells nothing but these garments.
The Electronic Arts offices in Redwood City, California, are liberally covered in the company logo to the point where it verges on self-parody.