I forgot to reset my cookies before I did a few offers. Does this mean that I won't get credit, or will it just take a little longer?
It depends on if you had a cookie for the site of the offer you completed. If you did chances are you are going to have to submit for a manual credit.
Could go either way. The most relevant question is if you have ever looked at the same offer on a different site.
But, I have done offers without remembering to clear my cookies and had them go through fine. So, it might or it might not. If you have to file a manual credit request, be sure to send your confirmation email with ALL of the headers. If you don't know how, there are several great posts here about that.
Yeah, it's never an all or nothing deal where if you clear your cookies, then you're definitely going to get a green (though happens like 95% of the time) or if you don't clear your cookies that you definitely won't get a green. It really just helps a whole lot.