This wasn't going to be the last expansion. Dark Ages was. Also, if you occasionally played games that used 2 or 3 expansions rather than playing full random all the time, you'd probably really like those sorts of cards.
I don't think there are any cards that are meant to be jokes or traps.
The issue isn't that guilds is last, the issue is that there was a planned, finite number of expansions in a game that's so easily expandable (as any keen fan card designer would know), so every card counts. I do like how each expansion is themed and synergistic (if anything they aren't themed enough), but with very few special setup rules, it's so easy to bring them into the fold and leave them there, that cards like Scout begin to stick out.
Thief is the highly likely to be a deliberate trap, as a card that steals opponent coppers, which seems like something that's reasonably good to a beginner player until they know better.
From the "Dominion Time Machine" post:
It would be nice if Thief were stronger, but it already scares new players, and once everyone was new.
I'm ok with this concept, but there's ways of making cards that initially seem good, then seem bad, that still remain useful at the highest levels of play (eg Workshop). Thief could have been replaced by a hint in the rulebook, or by having a card like Beggar or Cache in the base set (which would actively make players consider the true value of copper). The fact that Noble Brigand exists as a "fixed" Thief is all the more damaging.
Rats is also an example of a deliberate joke/trap card, which is actually useless outside of its combos, but it is easy enough to understand and strong enough when it works that I'm ok with it. Cards like Counting House which don't even work properly when you identify it's niche use are worse.