I appreciate the dynamic this conversation got due to my seemingly provocative reply
@JazzyPaws you got many things that i said wrong but i wont elaborate on that much, e.g. the "bad jacks" part was just a joke
Nevertheless, I still disagree with most of what has been said. First, I would like to emphasize again that it is useless to criticize incentivising wanted behaviour as not only everyone who has a dog does it but its essential for civilization in the context of human interaction. Second, wether or not one considers it to be sexual and thus all of a sudden "bad" or "deception" has nothing to do with the wellbeing of the dog but only your own subjective feeling. Of course I understand how one might get the idea due to culturally established values but this has no general applicable meaning. You must use your own intellect at times. My dog could lick my toes because 1. she likes the taste for some reason or 2. I put peanutbutter on them and she likes that taste. I also might enjoy it because 3. It gives me a foot massage or 4. It gets me aroused and makes my genitals tingle. In one example I incentiviced it and in the other not. Also in one it was for sexual purposes and in the other not. Does this mean one is bad or one combination is bad or all is good? All that matters is the effect on me and the dog and she would not mind it at all in any of the example combinations. Me feeling guilty or whatever due to it being sexual does not change anything about that, thats about myself and not the dog! If you dont want to do it because it makes you feel bad: dont do it. If it makes your dog feel bad: dont do it. If it makes both of you feel good: do it. Being on one level or not does not change this either and you obviously dont care about it when you train your dog for other purposes either which already clearly contradicts that idea. Also, it is something that usually is not even the case in human interaction. I would also like to encourage you never to argue with "what might the broad majority think of it" . History has shown that this is often a pretty bad idea and definitely wont help with progress. The examples of both being"better off" but actually are not like me harming you or not or giving an addict drugs are not changing anything about it because the examples are just wrong. You have a status quo and then ask wether it makes both better off. Negative deviations from it that keep the same relation or long term harm are obviously not making one better off. I am also a bit disappointed by some of the people commenting: you can do better!
TLDR: Your own emotions or ideas of ethical behaviour are usually a good guidance but it is not an argument, depends on the person, time, and culture and obviously cant reliably tell us what is right or wrong. Use your own critical thinking to find out why you think of something a certain way. If it makes both you and your dog happier it does not matter if its for hygiene, safety or sexual reasons.