The reviews and ratings of this website cannot be trusted since the service can be spammed and individual reviews are not vetted. What's more you're not protected against new websites that might be fraudulent.
Please see an independent review of this extension here:
Mostly useful. But its very easy to game this add-on to make misleading reputation. For example an owner of a site filled with virus could easily make multiple accounts of WOT and gives positive reviews about his site. Truly dangerous.
Very useful & satisfying web function, but when there is a significant difference between the public comments & the WoT calculated threat/trustworthiness, WoT should at least acknowledge the discrepancy, preferably explain it.