I agree with Motobecan69. I get plenty more life out of my ISIS bbs but its not nearly as wet here in Virginia. I do use antiseize on the threads because I find it holds up better than regular grease. Some peole use tephlon plumbers tape.

Irrespective if how well the cups are sealed, there are other ways for water to get into the shell if you are riding in the rain. Even if there is no drain hole in your shell, if there is a cable guide on the underside of the shell, the hole for attaching that is not water tight; nor is the seat tube. So you are going to get water down in the shell if you are riding alot in wet conditions; making sure the shell is draining adequately might help. If there is no drainage hole in the shell and you dont want to drill one, try removing seat and post after wet rides and hanging bike upside down to allow the water to escape.