The Roger Moore era is usually considered a Dork Age among Bond fans. Plots became weaker and campier, with more focus on gadgets and locations than characterization or action. Although this era did have its highlights (The Spy Who Loved Me) it also had its dark abysses (A View to a Kill, Moonraker). The Man with the Golden Gun is a Base Breaker, with some considering it on par with Moonraker and other fans feeling it to be Moore's equivalent to Goldfinger and much better than made out to be. For Your Eyes Only is unique in that it was a Roger Moore Bond film without gadgetry — it was given a mixed reception in 1981, but thirty years later, even fans who didn't like Roger Moore seem to like it. For music fans, on the other hand, the era is most often fondly looked at as the golden age of Bond themes, from "Nobody Does it Better" (Carly Simon) to "Live and Let Die" (Paul McCartney and Wings) to "A View to a Kill" (Duran Duran).
For a long time, the Timothy Dalton movies were seen as a Dork Age, with Licence to Kill being so gory and violent that many felt it barely resembled a Bond film. Nowadays, however, the Dalton movies are seen as prototypes for the Daniel Craig era, having had the bad luck of hitting about twenty years too early. In addition, the Bond that Dalton portrays is much closer to the Bond that Ian Fleming wrote: a stone killer and a womanizer with a hinted-at lust for violence. (Well, okay, all the Bonds are womanizers, but whereas Connery is the archetypal Bond-As-Playa and Roger Moore's just... well... Roger Moore, Dalton comes across as a sexual predator.) Craig himself can be seen as a Dork Age by the Moore or Brosnan fans since the plots had no science fiction plots by the villains for monetary gain which is seen as a detractor to some.
The Pierce Brosnan Age is also viewed as a Dork Age by some, and the consensus seems to be that it got progressively worse after GoldenEye (the only one with a Fresh score on Rotten Tomatoes), ending with what is often regarded as the worst Bond film ever, Die Another Day. Even Moonraker has a Fresh score on RT, although just barely.
Mae West lost a good chunk of her sex appeal when The Hays Code was imposed, but her movies remained passable. Myra Breckinridge and Sextette, made after she was convinced to come out of retirement in old age, are not. Myra Breckinridge was a terrible film in its own right and only featured Mae in a single scene — basically playing herself — as a man-hungry talent agent-type who gives the eponymous hero/heroine (don't ask) lessons on mistreating the menfolk. Frankly, Mae is not the grossest thing in it — not after you see the strap-on scene. Sextette... well, it was based on her 1926 play Sex, and having her be a Memetic Sex Goddess back then was quite a different matter from having the movie treat her like one when she's a frail, overly made-up 84-year-old woman paired with men young enough to be her grandchildren (such as 32-year-old Timothy Dalton, for whom this is a major Old Shame). Most people's reactions to the film are somewhere between a Primal Scene reaction and profound Squick.
Depending on your opinion, either Alien³ or Alien: Resurrection. While in popular culture, Alien 3 is considered the turning point of the franchise, many fans of the franchise appreciate the Assembly Cut's character drama (with an Alien...) approach, leading some to believe that the latter example is true turning point. To support its quasi-popularity, many fans saw Alien 3 as a return to the themes and atmosphere of the first film, where the second was a subverted gung-ho action flick.
The Halloween series had the extremely poorly explained Curse of Thorn storyline from the fifth and sixth films, which tried to tie Michael to prophecies, an ancient cult and the like.
The Disney Animated Canon has seen three Dork Ages. The first happened during World War II and a little while afterward, where all films released were cheap "package" films rather than ones with coherent stories, and ended with the release of Cinderella. The second happened between the late 1960s and the early 1980s due to the death of Walt Disney, and ended with the Disney Renaissance, while the third happened just recently, starting in the early 2000s and ended with the release of The Princess and the Frog.
Some argue the Marx Brothers went through this after their switch to MGM. Zeppo got tired of acting and the studio forced the brothers to go from completely anarchic Rapid-Fire Comedy to more good-natured characters helping out a forgettable romantic lead between increasingly tedious musical numbers (Groucho called The Big Store's "Tenement Symphony" "the most godawful thing I'd ever heard"). Granted, there was still plenty of CMOF, it was just more restrained than during their years at Paramount.
Then there's the straight-to-video sequels. Well, as always YMMV, but generally when Hellraiser fans recommend the series to someone they're usually only talking about the first two films - and maybe, possiblyHellraiser: Bloodline.