In this tedious economy one of my favorite mantras has become:
'I love what I do. I have a job.'
I've definitely had shows where I wasn't completely "on board" or enthusiastic about it. But sometimes working on shows is just that, work. If you can find any glimmer of enjoyment in the show, from the cast, to the music, to the lovely paperwork you generate, count it as some good experience and keep moving forward.
Case in point, the last show I did was a lot less professional than I had anticipated (read: I was put under the impression it was off-bway with an experienced team, when in reality it was a group of undergrad students putting up a show in an off-off space with no experience) When I was able to get past my grudges of being misled, I had an alright time trying to make the best of it...and the writer of said show has now asked me to SM his next show which will be a much bigger production.
Work begets work.