X2. Apply to the cloth first and then soak the area with the cloth. It stays exactly where you want it. The underside of the hardtop suffers the same thing.
Another tip I got from someone on this forum was to carefully apply soft scrub with bleach to the caulk line (not on gelcoat) and let stand overnight. Next day hose away and It should be clean. Sometime it gets inside the sealant and the only solution I have found is to replace the sealant.