Yea that is mostly right IMO. Sometimes (rarely) they will be "undercover" and wear plainclothes - you can usually spot them on the oversized handbags they carry where they store their scanning devices. Some are really good, very hard to spot them. But they always come in groups of 2+ and will enter at different doors and make eye contact with each other before they start controlling.

And yea the "clueless tourist" approach works almost always.