I have what looks like water spots on the spoiler and trunk lid on my prelude. The car sits alot under a cover and sometimes the moisture gets under the cover. Ive tried washing the car, quick detailer, clay bar, spray wax, and steps 1,2 and 3 of the mothers waxes. Nothing seems to work.

 

A buffing compound or aggressive polish with a cutting pad will remove the spots. If you use a buffing compound get something that has a good cut then follow that with a final polish. Use a good rotary and/or an orbital polisher.