Acoustic for the deaf?

There are tons of posts about how to make a room sound "better", but what about some of us that dont know what to listen for? Ive never been in a real control room I dont know what it should sound like. Ive mixed in rooms that have no treatment and added HI end and reverb until it sounded like a cathedral in the car! I moved to a smaller room even more live and the bass mix in the car is just over powering. I know you are all pros but how about some simple stuff that you assume everyone knows. Rule of thumb stuff like..... Speaker placement.- I see diagrams with the speakers nearly across the room from the mix position, then I read where they should only be a few feet away. Is there a rule? Low end- If my mixes sound boomy in the car deos that mean I have too many reflections or deos that mean I have too much absorbtion? Basicly is there a totorial or a test that will tell you if your speakers suck or you have acoustic problems or your just deaf?