Missing Trust

My repertoire of hustler-repelling attributes--default scowl, height, slow walk, cool façade that occasionally says I know what I'm doing, threat of an outright snarl--has served me pretty well in the ports, streets and plazas of Mexico, Europe and Morocco. But another attribute tends to get me in trouble: my desire to trust people. Earlier today I was claiming that apart from paid staff in hotels and cafes, I can't trust a single person in Morocco. Not one. This applies to the taxi drivers who won't tell you the fare until you get in--so don't get in until you agree on the fare, Gerry--the hustlers in the doorways of shops, and, most insidiously so far, the friendly types who approach as if trying to help you out.
Here's an example of this last type: This morning I'm enjoying a compartment to myself on the Tangier-Fes train. A guy comes in, introduces himself, starts talking/asking--so, politely decline to answer, Gerry--and offering information and invitations to this and that, even showing me photos of his brother in Vancouver. I didn't trust him, then I did, then I didn't. At first he said he was going all the way to Fes, then--once I'd begun to keep my nose stuck into my e-reader--he announced that he'd just received a call from his family, who'd invited him for a meal, and he got off the train. He'd given up on me, or taken pity on me, or extracted enough info (including the name of my hotel in Fes) to renew his campaign later. His closing words were, "People will come in here at Menkes and act friendly the ask you questions and tell you things. Don't trust them." !!
Here, then, was something I'd read about. The authorities in Fes had cleaned up the area around the train station, so the hustlers had taken to boarding the train a stop before Fes, giving themselves a half hour to work on the rubes like me.
But I must correct myself. I trusted the really old guy in the medina yesterday whose shop offered a beat old collection of old photos and prints and books. He hadn't said a word, just shifted a little to let me into his shop.
This hustle thing bugs me the most about Morocco, in the limited time I've been here. Maybe in more time I'll see this as a game and enjoy it. Right now I don't. It closes my heart to this country (though, later, first forays into the Fes medina start to open it again.)