He swears that you should only use gasket sealant on one side of the gasket.
This is the same way my dad taught me to use sealant but for different reasons. If you coat both sides you can displace the gasket when tightening the part down. The only exception I make is with oil pans as I tend to lean on the heavier side with the sealant here.
Like said above, cleanliness is the most important part.
Jeff
