So I ask you, Americans and others, am I grossly overgeneralising here or is there really a lack of subtle comedy in the American sense of humour?

comedians are awful.

I've seen alot of American comics try and fail miserably at irony, for example, but irony is a harder thing to achieve than one might think so that is understandable. I never see American satirists though. I'm sure they must exist, but not in vast numbers. There are two exceptions I know of. The first is Jon Stweart, I watch the daily show occasionally and I usually enjoy it although it's a bit too wrapped up in American politics for a foreigner like me to fully appreciate it. The second is Larry David, again there are a few jokes where I think some things have been lost on the journey overseas but I think its a friggin hilarious show.

neither of those shows are any good. this is not feh!! ignorant american doesn't get the humor!! -_- they are just a couple of shows that have their moments but are usually awful. I like how curb your enthusiasm perpetuates HBO's QUALITY IMAGE (stella artois) by advertising itself as an intelligent comedy. well it must be good!!! it's not, it's actually pretty dumb most of the time.

someone should make fun of your post I don't feel like it

Hmm...I think Willem T. Taft has something to say about all of this:

one of the problems with jim gaffigan is that he sucks all the fun out of stand up by doing that schtick that he does where immediately after he tells a joke he goes into his little 'audience voice' that tells a crowd exactly what they're supposed to think.  he is probably the most milquetoast comedian i have ever seen.