Wash, then wear?

When you buy a new swimsuit, do you wash it before wearing it? Do you run it thru a washing machine with detergent? Do you hand wash it? Or is it no big deal because it's being worn straight into chlorinated water which will kill any germs?

Do you believe it has never been tried on before without underwear? Do you not buy it if the hygiene sticker isn't still on?

What would be the main hygiene concern? Crabs?