well the thread wanted to know what to look for right, so now he knows. The guy says its a garage conversion. Having a floor off an inch or more is wrong. It will suck if his table is off alot and not an easy fix later as he will have to remove his table and level his floor. Some problems should be corrected before hand or at least known about, wasn't that the point of the thread.
I wouldn't just put a table anywhere and then address the concerns. I think he should get someone in there if he can't do it and get the floor level. It doesn't cost much and its easy to do before the table gets there.
The guy most love pool as he is converting his garage. I assume he is some sort of a player and therfor a table heigth difference would be his more serious objection. Of course depending how tall he is will matter also. I have a friend who is 5' 6" and when I have an antique set up at my house he doesn't like playing on it because one side is too high and he can't bend over with any comfortable stroke. If there are young kinds playing on that table in the garage it will suck for them to if one side is much higher than the other..