[tiffanysmummy]

I find that even if it's cloudy they still usually come out as there are uv rays even without sunshine. If it's raining, I have to dry inside but the stains usually come out with the next lot of outside exposure. Some tough stains take a second exposure to get completely removed.
I've got BG pockets too, and I've found over time my inserts have yellowed (not stained, just changed colour), but I'm sure a soaker of some description would bring them back to white. I haven't bothered though, as they aren't seen anyway.