Rating System Abuse

Rating on the listing page is one of the most important factors in bringing a decision about buying an item/job in the listing. I think it’s rather dangerous to allow anyone to post rating on the listing even though they never actually purchased it. Anyway, how can you give your opinion on something you’ve never tried?

When users discover that they can give bad rating on other people’s listings, it’s guaranteed that they will abuse the system to make other people’s listings look bad. I am hesitant to let my website go live with a rating system that can be so easily abused.

Does anybody know for any way to avoid this, or the only way is to send a support ticket to Mark Fail and ask him to include this in the next update?