As an Offspring fan, sure this sounds like an awesome idea. However, I can't imagine your average bar scene being thirsty for an entire set of Offspring covers. Most people won't know a lot of the songs, and bars (generally) look for bands to play a variety of well known songs from many bands. Being in an Offspring cover band could be a lot of fun since you are playing great songs from a band you love, however I'm not so sure it's the best idea if you are actually looking for gigs.
I would keep Spare me the Details and Can't get my Head around you. I'm a little iffy on Stuff is messed up, I say this because I know that those 2 songs i suggested you keep will keep the crowd entertained even if they don't know offy but Stuff is messed up is more of a song that probly won't go over too well with a casual listener.