Some waxes (cleaner/waxes) contain abrasives to smooth the surface and remove blemishes. Rubbing compound, gently applied, and claybar are the normal ways to remove surface contamination. If you use a cleaner/wax, you will have a coat of wax over the contamination after you are done, making further rubbing compound necessary if there is any contamination from the other vehicle's paint remaining after application of the cleaner/wax.