There's an article in The Guardian from the films director which is worth reading.
https://www.theguardian.com/film/2004/feb/27/2
What he doesn't seem to get is that being crude is not shocking or offensive anymore and it can be funny. There are plenty of very crude films i've laughed my head off at as i'm sure the film critics who panned his film have as well.
I'm sure i'd have enjoyed the film a lot more if i was as drunk as a skunk with equally hammered mates but i wasn't. I was hoping for a few laughs though which should have been achievable no matter my level of intoxication.
I actually like Vegas (I've had a beer with him after a small gig in Colne where he constantly took the piss out of us during his act), Crook, Gatiss and Julia Davis (Have you seen her series
Nighty Night? - very dark and very funny), so from a casting point of view i looked forward to the film. In fact the actors were all pretty good. It's just what they had to work with was largely a one trick pony which although crude ended up being not very funny as swearing soon grates when it takes the place of actual comedy. The jam and fish joke was initially amusing, but the script used it at least eight times so the comedy value wore off really quickly.