Again, IT DEPENDS!
A paint booth should move enough CFM to both produce good paint jobs and meet OSHA requirements of 80-100 feet per minute. OSHA requirements take into account the booth space, the CFM, and the draft pattern. Your paint booth manufacturer should meet OSHA in all of its paint booths and be able to tell you this information. A paint booth should also move enough CFM to produce a strong draft for good finish quality. The minimum required is meeting the OSHA code but real life is different. As you use the booth and clog filters, performance is going to change. You want a paint booth with strong CFM so the performance is great through the life of the paint booth intake and exhaust filters. If you get a paint booth that just makes it past OSHA code with clean filters, it more than likely won’t be a very good paint booth when you actually start using it and clogging filters.