Currently, the basis of "don't forget to vote" is:
you haven't been seen on the target site for 24 hours
you hold a valid user cookie on the target site
your account has more than 15 reputation on the target site
you arrive on a question from a search engine
you have not already voted on this particular question and answers
This is mainly annoying to regular users of Stack Exchange - in my case when I occasionally come across Super User while Googling.
I can think of two ways of avoiding annoying the regular users.
One is to change the first criteria to
- You haven't been seen on the Stack Exchange network for 24 hours
Another would be to only show it to people with a low overall Stack Exchange reputation.