Our shower has been draining very, very slowly. We have a hair catcher that seems to be working well (it catches a good amount of hair). I tried running a snake (two different sizes) down the overflow but it doesn't catch anything before I can't go any further. It appears we have a system like the first diagram in this answer, except there is no Trip Lever or stopper (I've tried removing it, but I haven't been able). So I think that the snake is too big to fit through the spring. I've tried using a plunger (with a wash cloth over the overflow) and various Drain-o like products. But nothing seems to help. Anything else I can try? Or is it time for a plumber?
Finally got a plumber out. Apparently the device should have been removed when the previous owner redid the bathroom, so now it's sort of "stuck" or a part of the tub. It can be removed, but will be fairly costly to remove. The plumber actually broke his snake trying to get down to the clog, so it wasn't just me having problems. Fortunately, the tub seems to be draining a bit better these days.