I think some bands put together a show and only invite other
bands on the bill that they know they can out-draw and thus, look like
the biggest band... And end up collectively pulling in 40 people (if
they are lucky) between 4 bands... Of course, this is the "metal"
scene. I don't know about the other genres in town.
That's when the bands themselves are putting together the lineup of course. When the bookers or outside people put them together, they don't always seem to look into what the bands sound like that they are booking together, so you end up with a lineup of an extreme metal band, a screamo band, a rock band, and an over-the-hill rockers metal band... all in the same show. It's silly. Maybe they DO know what they sound like and just don't care. I don't know.
Of course, that's not all bands and bookers: I am well aware that there are people that are doing a good job as well. It just seems that there are a lot of shows that just don't make sense: it's pretty hit-or-miss, and it has been going on for a good couple of years now.