Do offers dry up?

Ok, I'm new here, and though I think I know how it works I have one more question.

And I did look for a thread answering this question before posting this, so if it's been covered before, please be patient with me.

Can you do so many of these things that there aren't any left to do? I mean, you can only do each offer once, so are there few enough of them that I have to worry about running out?

Oh, and one more question (I hope I don't sound too dumb).

If you are only supposed to do each site once, why is it so important to delete cookies?

You will probably find that you start running short of offers, especially if you do a lot of sites within a short time period. Over time, though, freebie sites drop old offers and add new ones so you should be able to wait and find another offer. Of course, with FreePay, you can't wait because of the time limit, but you can with other sites.

It is important to delete cookies because you may have been to the offer page before (even if you didn't complete the offer). Say you are on your FreePay Ipods account, you check out some of the offers, but you don't do any that day. Then, a couple of weeks later you sign into your TRAINN iPods account, click on an offer, and do it. If your computer still has the cookie from when you visited the offer the first time, you might not get credit for doing the offer through TRAINN.