4.2 in SF location. So this is very good info. That's the baseline. Below 4.2 => DO NOT CONSIDER.

I know on ebay and amazon I do not buy from sellers under 99.6%, as an absolute minimum.

It's ok for the system to be gamed, as long as one can understand the rules.

A bit of a tangent, but I feel like I have also created an artificial scale on a rating system myself. I use Untappd to score beers. But it turns out there is a pretty wide variety of beer that I like so most of them end up as 4 +/- 0.5 our of 5.

But I'm not the only one. The overall rating system most beers end up in the 3.5 to 4.5 range. Where 4.5 becomes "oh my god, these brewers are doing incredible things with this beer" and 3.5 becomes "ugh, this tastes worse than bud light"

Ah not far off from the scale used by video game critic site IGN:

“This game is trash” - 8/10

The eBay ratings - despite being numerically the most egregious - are probably the most helpful. 99.6% ostensibly says that there's a 0.4% chance of you having a bad experience. Star ratings don't really convey any meaning.

I'd definitely adjust my baseline "acceptable percentage" based on what I'm buying. If I'm getting a pack of USB cables for $0.05 each, I'm not going to be too fussy about the rating. I'll take a 2% chance per cable of them not working, that's what I'm paying for. If I'm buying a new GPU, I'm going to be a lot pickier about it.

The formula for interpreting a rating out of 10 on an Uber service is (rating - 4) * 10.

It has to be very bad to dip below 4, so that 4.x is the only thing you really can look at.

I'm not that strict when it comes to things. I sell a few things here and there on eBay, even a 4 star review would easily pull me below 99.6%.