I'm with Setec...can't hurt and certainly better than not putting anything on.
I had a neighbor recently ask me if i could "help" him wax his car. Sure. The problem for me was that i couldn't talk him into either my services OR doing anything more than a wash and a wax. The only thing i was able to talk him into was to ditch whatever crap he bought at the local auto parts store for "wax" and let me lay down some Blackfire. He was still hell bent on using his dish soap because "dangit, that's what his father and brother did!". Ok. No problem. With someone like this i will make a less than energetic attempt to change their mind...they'll still insist their way is better and thats that.
His request included him doing the work and me simply "helping". We washed his truck (brand spanky new metallic F-150 Lariat, BLACK!), dried with my MF towels and we were ready to go. At this point i was able to convince him to let me wipe it down with some CarPro Eraser and thus my point here. I wanted to clean the paint just a smidge more if its only a wash and wax, especially with sealants. I like Eraser but if i didn't have it i would use iso alcohol. Just to insure the sealant has raw and exposed paint to bond with. Takes minimal time too.
