Now I monitor my account frequently and I had not the opportunity to receive their message. Therefore, Sprinks links are not requested by spiders and no charge is passed to the advertiser. I am not a Sprinks customer, so I can't speak for your setup. However, many spiders have the capacity to crawl dynamic links. Rouge spiders do this routinely.
Dynamic links are a very thin shield against spider hits.
Session ID tracking would be a much better approach. Like Google Adwords where you have a preset spending limit. When you sign up for Sprinks, you will only be charged the amount you enter. You will not be charged for any more than that amount, until and unless you authorize it. Wow thanks for posting here Colette.