If you have a bad gut feeling about it then I’d definitely pass on them.
I usually check to see if they have social media such as Facebook or Instagram, and see if their pages seem legit. I’ll also check their MorphMarket store ratings, if they have any.
If they don’t have any other social medias, I usually steer away from them. Especially if they’re a new seller. I may take the chance if they have several good reviews on MorphMarket.