Unsolicited cold calling
I got a call from these without me signing up for anything; the guy explained that my details were provided by their marketing research (could be anywhere because this was a public business number).
When I said that I'm not looking for any product and "I don't want to waste your time", he rudely hanged up without saying a word.
Cold calling + Rude = dodgy; serious companies with worthy products don't burn bridges that quickly
