Sorry, but this thread is utterly ridiculous!
Some kids are chancers, others aren't, the kid in question is a chancer, SO WHAT?! My ds would never lick anything someone else had licked, my dd1 would quite happily chew gum from someone else's mouth, not nice, but there you go.
He asked for a lick of your lolly, you said no, what's the big deal? Posting on mn about it IS weird imo. Same goes with the toys.
Whenever a kid asks me anything like that, I just laugh and say no, more often than not, the kid laughs too because they know they're just trying their luck as much as I do. Not all kids who are a little bit cheeky and trying it on have asd, that's absurd!
My dcs often go to my dm for a few nights in the hols, their friends knock every day they're not here, they're not being rude or nasty, they're just being kids and can't remember what they were doing 5 mins ago, let alone I told them yesterday dc's aren't back for a few days!