its not always a matter of the pa being an afterthought though, i've played spots that werent the best in terms of upkeep to the bar itself, but had more than adequate soundsystems. with the price of pro audio gear being as low as it is in this economy, you do see more places having decent gear these days, and if you dont inquire about that, then theres no reason to complain, especially if you are just looking for a show. it really depends on the spot and another big factor that ties into the equipment is how often they run shows, whether they see enough revenue to justify spending money on new house equipment, the size of the venue, and here we go down the rabbit hole.
you've got whoever was setting up the pa system in the club and whether or not they thought to use separate amps for l/r channels, or amps that do stereo, thats the dealbreaker of the equation. then you have the issue of competent soundguys who are able to roll with the punches and go to extra lengths to help you sort out the sound issues, which is why i suggest always talking to the soundguy when you first get to the gig. of course, the biggest issue next to whether stereo is even a possibility is whether or not you punish the soundguy during setup/soundcheck and how willing he is to work with you. its my feelings that if you are playing in a place that is bigger than ~100-150 capacity or so, you are shortchanging the audience by doing stuff in stereo.
