I have a classifieds site, and I've allowed people to post reviews for several years. Those reviews aren't used as often as I'd like, though, and with many people texting instead of messaging through the site there's no real way for me to know when a transaction is complete, or even know if anyone has contacted the seller at all :-(

My system just has the reviewer give a Thumbs Up or Thumbs Down, and then they can give an explanation. It's loosely moderated, so sometimes we'll remove the review if it seems like a joke or something, or if the seller can show that it's totally false.

The rating simply divides the number of positives by the total reviews. If they have no reviews then no rating shows; if they have 1 positive then they have a 100% rating, if they have 1 positive and 1 negative then they have a 50% rating, and so on.

The long term problem there is that someone could be selling for YEARS but never get a positive review, and then get a single bad review that gives them a 0% rating.

So here's my question.

Let's say that someone posts a negative review for a seller, and it's that seller's first review. Now they have a 0% rating.

But then the seller replies to it: usually giving their alternate point of view or some sort of explanation for the negative experience, but sometimes just arguing.

Should they still have a 0% rating? Or should replying to it give them some sort of bump?

Or maybe I should consider how many ads they've posted, total? Or how old the account is? Posting 50 ads over 5 years with 1 negative review feels different from a new user that's posted 1 ad with 1 negative review. But I don't know how to math that out.

This exact scenario was brought to my attention today by someone that's been selling on there for 10+ years, and I'm kind of at a loss. I agree that they don't deserve a 0% rating, but since it's their first review then that's what is showing. And I can't think of a way to weigh it more fairly. I don't want them to leave the site, obviously, and I don't want their sales to suffer unfairly. But at the same time, I have to be conscious of those new users that get a bad review and do deserve it, and I have to be fair for those reviewers that honestly had a negative experience.