Ive used quite a bit of vinyl dyes both SEM and PPG. Those hold up rather well with proper prep, Can't vouch for the over the counter spay can stuff myself. I wipe them down several times with prep-solv to remove any mold release agents, spay a coat of adhesion promoter(Bulldog or something along those lines) then dye. A couple easy uniform coats and done. You don't want to build to much mil thickness because of the expansion rate of plastic. Check with your local paint jobber if you don't have spray equipment. My local store will load sem products in a spray bomb.