The price is about $2-3 so you are not risking much, there are reviews and ratings. Of course there are scam sites, but once you buy several accounts you quickly figure out which ones are scam and which are not. Bank cards (sadly for larger sums only - probably difficult to find a merchant) as well as cryptocurrency are accepted. The interface supports Russian and English languages which points at the country of origin.

Re: stolen accounts, you can examine account details, history and activity after purchase, check for emails from social networks and return stolen account to the owner. The posting usually also mentions registration period (new accounts are unlikely to be stolen). But it seems that registering new accounts is cheaper than stealing - old accounts are much more expensive.

I didn't use the account for any illegal activity, there are just sites that use Google Account as a "verification" that you are not a bot, and to issue bans. And I am not interested in jumping through the hoops of searching a locked smartphone with Google Services and filing a visa application to register the account. I strongly dislike proprietary software and locked smartphones.

Also avoid buying Facebook, it's paranoid and with high probability you won't be able to login unless you use some "correct" combination of anti-detect browser, proxy and provided cookies. But Google, VK and Telegram are usually ok to use from different location if you don't do stupid things like logging into multiple accounts from the same IP and browser.

Markets are regulated by reviews, seller history and so-on, the same as legal markets and it's generally smooth.