Not sure how your lenses and housing might be now. Normally a bit of water can intrude in the front. But it can't get trapped and will run right back out. The chrome rings around the lenses actually help with that too. But it's the water that comes in from the rear that's the real killer.
It gets trapped behind the bulb and socket eating both. Then the slightly corroded and otherwise messy water slowly leeches forward in to the housing and causes more mess.
Maybe mine are busy doing that behind the reflector where I can't see, but I can say for sure that A LOT of water and grit goes in the front (especially when I wash the bike, and while most of the water may run out, the grit remains, and at least some water, because they steam up. I have to remove the lenses c/w chrome rings every time I wash the bike to dry inside, and periodically I press the lens out of the chrome ring to try to clean out the mess of grit (no black eyed peas though!

) that builds up in there. Shockingly cheap and poor design, even for Harvey Donaldson's Chinese Emporium.

Jim