I just know I used to get all excited about a notification in my inbox, and then disappointed when it was someone thanking me for a fav or something. Now I'm just "eh" it's something xD But for that reason I can definitely understand why some people don't want to be thanked, so I skip those, and I skip the ones who have like... borderline animal porn in their galleries because then I just get really uncomfortable about why they're watching my art <.<Everyone else I thank for watches. Not really favs though as whenever I go to do that, they usually have like 30 thanks comments in the past hour and then it doesn't seem like my thanking will be particularly appreciated nor was my art of actual note, more just spreading their name it seems.