Not just borderline. Most of the ones that can feasibly run a game for example are basically real malware.

Do you mind elaborating on this? Is it just because the use case turns into something like app install fraud?

It's everything from a mix of cryptominers being deployed quietly (since of course anyone installing these will have a low end or better GPU), app install fraud, review fraud, Play token theft, spyware-tier telemetry. Even on the ones that don't install anything bad at all, they tend to auto-install the lowest common denominator apps via advertisements or paid placement that then have their own absurdist SDKs or whatever for data collection and mining.

Pretty much any of the closed source emulators that can feasibly run games (i.e., be horribly abused en masse for botting games) are festering piles of crap.

Another super common thing in those low tier trash apps is using your computer as a proxy ala Hola. Pay-per-install for using you to run stolen card traffic.

I can run most games on the Android Studio emulator without much of an issue, though it takes a higher mid-tier system to do it.

Which games? I don't mean like Fruit Ninja or Candy Crush, but the games that people actively bot or abuse will have a ton of ridiculous bullshit (checking anti-root, safetynet, borderline malware or malware-esque SDKs that exfiltrate huge amounts of data)

You're right, probably nothing that would be the target of bots like that, so I don't know how well those would work.

I play a few games my kids got me addicted to, Williams Pinball, and miscellaneous niche games. They run fine. But I haven't tried some of the popular MMOs or games where farming is basically the point.