The other thing to consider is how well A students in AP courses do on AP tests. If the most common AP test score for A students is 1, then that is not a good sign.
However, few high schools or districts give information of that detail. The Houston Independent School District does; see figure 5 of http://www.houstonisd.org/site/handlers/filedownload.ashx?moduleinstanceid=73138&dataid=123661&FileName=Advanced%20Placement_AP_2014.pdf .