Using an AP Test for Placement (not a question about AP credit)

My son took the AP Chem test yesterday but is thinking that regardless of his score, he will probably re-take Chem in college, partly because his Chem 1 teacher was a great guy but did not give them a good foundation. I have a feeling that attitude will not get him a 5! He should do well on calc, but good idea to talk to the college about what level he should start at. I had originally thought it would be good to take the credits to have more flexibility, but getting a college-level foundation may be even more important.