The red flag is simple, and it is if the recovery site ask you to send them (the recovery site) money (like bitcoin), that they will recover the coins for you, know that you have been scammed again. I mean those online recovery service.

99% of the online recovery services are scam. This is enough for people to learn how to do it by themselves.

If you send coin to a wrong address or a scammer, first research if the address belongs to an exchange or not. If it is not sent to an exchange, to recover it is difficult.

If someone scammed you like $1000, that is very small for legit recovery services. They prefer to trace huge amount of money like $50000 or even more. You will need to contact one of the Chainanalytic companies for this.