Wolf, are you familiar with ASMR?
I have that. I have sat through countless sales presentations simply because I get the ASMR tingles from them. I have never disclosed "I have ASMR" before the presentation. I am getting a non sexual thrill from them without them knowing it--somehow I don't think you see it as nearly as wrong.
But the sexual part or pseudo-sexual one you do. Which again, to me, is a sign of a sexually repressed mind born of a sexually suppressed society that wants people to be ashamed of their sexuality and urges.
If the act itself is not wrong--as you say before...in a friendly spot where tickling would be acceptable anyway--then yeah, I don't see the problem at all. Because clearly the ACT doesn't bother them.
"But the motivation might bother them..." to me is a paper-thin argument. No one has an automatic right to know your motivations just because they engage in something socially acceptable with you. If they are worried about your motives, they can simply opt-out if thats how they feel. But this quid pro quo full disclosure everytime something MIGHT turn you on, is just stupid, awkward, problematic, and frankly, childish.