Dude, I've mixed in a corner for a long period of time, and if you can get out of the corner, DO IT! Not only do you have no idea what's going on in the bass, but you get stronger reflections from the monitor in the corner, which means any stereo imaging you're doing is all screwed up. Not only that but the levels of any instruments panned on the corner side will sound stronger. I personally am tearing down a wall and moving everything around to get out of the corner. If the fix is as easy as getting a stand, do it. There's good DIY info somewhere here on how to make your own stands, too.