Uhhh...I find pats on the back from strangers to be incredibly rude, patronizing, and uncomfortable. Do that to me and I'm likely to just walk away but not before saying "don't touch me."

Pretty bold of a salesperson to grab your forearm, or other obviously flirtatious moves though. Might even risk the opposite of the intended effect.

Is that common, or is it usually more subtle, like touching your hand when passing a pen?

A touch on the forearm is what I`ve experienced most from saleswomen, a breast press on my arm has occurred more than once. Always* during a negotiation when I was the prospective buyer.

*Excluding social interactions.

They touch you to make you feel something when they say the words.

The pros even touch you at a specific words in their sentence so you subconsciously remember those words.