They were unfunny ever since they came back from the cancellation. The problem is that their jokes have really shifted away from the characters and more towards the cutaway jokes, which were much rarer in earlier seasons. If you look back, original Family Guy humor is a lot different than it is now. The three biggest things that irritate me that they do:
- Referencing Old Stuff is Funny! Anyone ever seen the "Comedy" episode of Metallocalypse? There's a comedian who gets laughs by mentioning 1980's cartoons. "Remember Snorks? Snorks! I'll give you a Snork!" That's what Family Guy is now. It thinks that, by simply mentioning something old, it's funny. Sometimes it is (The GI Joe parody), most of the time it isn't.
The Longer it is, the Funnier it Must Be! When did every Family Guy joke pull out to 3 minutes each? I think one of the reasons I liked Star Trek part of the recent episode was because there were actually a lot of different jokes being thrown out in relatively quick succession. You can only stretch a joke out uncomfortably for 58 seconds a few times before it becomes really, really irritating.
Preachy Bullshit! For some reason, American Dad is just a whole lot better at being preachy without being really, really irritating. Using the Star Trek episode as a reference (Since it's the only episode I've watched recently), the whole Meg plot was so heavy-handed it had it's own gravity well, and it came off as stupid and illogical unto itself. I don't mind preachiness sometimes (South Park and American Dad do it well, and old Simpsons episodes knew how to do it), but Family Guy just has no fucking clue how to be interesting with it.