We use Best Match -- an algorithm that determines if a listing belongs to a profile. Best Match compares the anchor data (Name, Address and Phone Number plus Website) to the information found on the listing, determines if a listing is worth considering and then ranks the listings on how closely they match the anchor data.
A listing's page is determined as a "potential listing" if the best match score reaches a threshold. By default this is 50% (145), but on some sources we expect a better score or don’t expect as high a score. For example: Twitter pages don’t allow users to enter in much information, so its threshold is quite low. Whereas Yahoo! Local has a lot of information and is usually quite accurate, thus its threshold is rather high. If none of the listings returned in the search reach the threshold, there is no Best Match, otherwise the highest scored listing (or listings in the case of a tie) are the Best Match listing(s).
Best match considers phone, name, city, zip/postal and address independently and scores the match between 0% and 100% for each. Each type of data has different weighting on the Best Match result:
Phone Number has the most influence and city has the least. A perfect score is 290, but anything above 257 is considered a tie, since a profile could legitimately have multiple listings on a site and any listings scoring at least 257 are likely real listings.
The match may also be dependent on your visibility settings (Strict vs. Relaxed). Note that if a listing has recently updated, and information matches, but is still marked as red, it is because Best Match has yet to run. It should run shortly after the listing updates, and the red marking will disappear within 30m.