How much does chess.com determine who you play?

I've been playing chess for over 10 years. I'll play against an coffeehouse opening that i've never seen before lose and then all of sudden i'm seeing that opening from different users frequently until i start beating it and then i'll never see it again.

If i play 8 moves and leave again my next game my opponent played less than 10 moves and leaves the game.

I know premium members get better queues and toxic players get queued with each other but just how far does this go? Can this be used to control someones rating, and is it ethical?

I have noticed some of those things too and wondered why they occur.

I have never seen anything that documents what Chess.com does to match players other than the things you mentioned.

Great question, Andrew. I have had the same issue with openings that seem to come up in clusters. Additionally, I do recall quite some time back that there was a comment somewhere on the site that people who habitually demonstrate poor ethics, ie. abandoning as one example, are often paired together, although I do not know if that practice continues. I think some elucidation on these matters by the administrators of this site would be a great idea. Have you given any thoughts to sending your query to Chess.com directly?

I don't know to what extent this is true, but the repeated openings seem like they're the same people on different accounts, or it could be a coincidence. Assuming everything is as you say, this would only do a lot of harm; it would create a false perception. If toxic players are grouped together, the toxic player will justify himself by claiming everyone behaves the same way he does, so he won't have a reason to change his behavior. Pairing players based on their behavior creates a damaging island effect; it's more effective to rely on the reporting system; but a system to isolate players based on their type is, I suppose, cheaper, because the reporting system requires many people to ensure it's working effectively.