When postage stamps are first invented, Moist wonders about a method of separating them from a sheet without having to go through the long-winded process of cutting them out one at a time with scissors. He remembers how Stanley secured pins to paper - by pushing them through it - and, being Stanley, this leaves a long precise line of regularly shaped holes which may be torn. He describes this to the techs at Teemer and Spools, who then build a machine to create perforations. This has apparently never been done before, and Moist gives T&S the copyright and patent for the machine. Yet much earlier in the book, he visits Dave's Pin Exchange and explicitly asks for - and buys - a roll of pre-perforated backing paper to display pins on. So the technology for making perforated paper clearly already existed on the Disc? he didn't need to re-invent it!
So, you were expecting him to, what, lift up her tail and check her groin? And what difference would it make if he had guessed her gender right? He was just making observations, not giving her a bloody physical. Lighten up.
I'm guessing the difference it would have made would have been when Moist was sure that Nobby was the werewolf.
Moist was never sure Nobby was the werewolf — near the start of Making Money the narration simply notes that it's "widely rumoured" to be Nobby. Moist doesn't seem to have given the identity of the werewolf any real thought until he realises it's Angua.
(S)he may have been mistaking Moist for William de Worde from The Truth who knew about the rumour of a werewolf in the Watch, and is damn certain it's Nobby - he says so to Vimes and - if I remember correctly - to Angua herself.
Not to mention his knowledge is of dogs, not werewolves. He knows a lot about dogs, so he knows she's not one. He doesn't know about werewolves, so he doesn't know she's a she.
Angua's fur has always been described as fairly long. That in itself would suffice to conceal any clues as to gender, particularly if Moist only sees her from the front.
What exactly did Crispin Horsefry have that Gilt killed him for?
A little knowledge and a lot of cowardice, that is what Horsefry had and why Gilt had him killed. Crispin knew too much, not everything, but enough so that he could start everything unravelling if he cracked. And Vetinari was applying the pressure. Worse still, he'd written everything down in a little book which he gave to Gilt for safekeeping, once Gilt had the book all he had to do to shut down that line of enquiry was shut down the only other possible outlet. Which was of course Horsefry himself.
Once, it's revealed that Golems can "Speak With All The Voices Of Men" (and don't capitalize every word when doing so). Imagine what someone like Moist would be able to do with that small tidbit of information, because that's all you're able to do, imagine. It doesn't come back later in the book, or in Making Money. Anyone know why?
Because the books after this, barring Making Money, haven't had Golems as an integral part of the plot. As for Making Money itself, Gladys had no reason to use it. As for the Ancient Golems, there was no telling if they could do that or not, and Adora, and anyone else barring Moist who tried talking to them, couldn't get though to them as is and Moist was flying by the seat of his pants as usual. It was also a pre-recorded message, so theres no telling if Golems can even do that at will or not.
Moreover, golems are so very honest by nature that it's questionable whether even Moist could talk them into exploiting such a talent without a very good reason.
During the "job interview" at the beginning of the book, Vetinari points out Lipwig's option to walk out the door, and Lipwig decides to investigate the door and notes the lack of floor beyond it. Less than one page later, going by lines, Lipwig has accepted the job and Vetinari has wondered why he hasn't left yet. (Admittedly in character for Vetinari.) Less than one page after that, Lipwig has left the room without description. While there are a number of ways one could design the exitway to make this feasible, it seems like a waste to simply drop the subject like that (for this scene, anyway), not even allowing Lipwig the opportunity to ruminate on the now-solid flooring.
He used a different door.
Agreed. Also, Moist had to come into the room by some means. Even Vetinari had to and it is highly doubtful there would be a one-way entrance to the room. The Patrician doesn't seem the type to have a slide-entrance. It's just the door referred to as the exit that has the hole in it.
It's possible it's a similarly-designed but entirely different office, as well. He was brought to the first one in a hood, so wouldn't have been able to see where he was going. Office 1 has the Door of Doom; Office 2 has the door of no-doom.
Why doesn't Vetinari audit The Grand Trunk whenever he feels like it? There is a line near the beginning of the book about not being the sort of autocrat who just locks enemies up, but people hate the Grand Trunk from the start. Vetinari wouldn't lose any social capital by going after them.
Even if they didn't like Gilt, there are powerful people in Ankh-Morpork who wouldn't like the precedent it'd set. Part of the secret of Vetinari's long tenure as Patrician is that he doesn't let himself seem to be ruling much of anything: he graciously asks the Guilds for their input all the time, sets up loads of committees where their opinions are duly aired, then does exactly what he wants to do while thanking them for "suggesting" he do so. Suddenly breaking this habit to slam down an individual business without due process would upset a lot of factions who've come to rely on his steadiness.