I'm very curious what your take is on revealing your current salary to recruiters/potential employers early. Do you tell them early to avoid wasting your time?

I'm very curious what your take is on revealing your current salary to recruiters/potential employers early. Do you tell them early to avoid wasting your time? For myself I'll just say that I've done well since I realized that I should negotiate for EVERY offer I'm given no matter how high. There are no more exploding offers after you've had a couple jobs - we're not in kindergarten and our parents aren't going to take things away because we're acting selfishly.