Planet13 - 4:39 pm on May 20, 2011 (gmt 0)
Also, check how well the page that has the questionable link ranks for keywords that are related to the keyword for which you are trying to rank. If you sell widgets, and that page that links to you doesn't rank well for any terms that are widget related, then it may not have much value.
Also, look at the pages that are linking TO the page that is linking back to you. If those pages are not related to your product, then again, the value might be questionable.
Out of curiosity, how much were you spending on paid links per month (or per year)?