Yeah, I really don't like the trope of "women don't like guys who are too nice" because it's rarely about being too nice--it's often about showing no initiative, or being boring, or being too passive, which are all way different than being nice, which I equate to "kind". I have never known a woman to not be into a guy because he was too kind.
I think too many people confuse "nice guy" (= guy who is kind) with "Nice Guy (TM)" (= guy who believes he can "nice" his way into a female friend's pants). Nice Guys need everyone to see how nice they are, how supportive and wonderful they are, because they believe they should get credit for every nice thing they do and eventually, somehow, all that credit will eventually transform "friend" into "girlfriend." These are the guys who whine and complain about how girls always end up with pushy alpha guys - completely overlooking the fact that women (we're not "girls") generally choose our romantic and sexual partners based on compatibility and respect and attraction rather than who buys us the most lattes and gives us the most rides when our cars are in the shop.
I knew one of those "Nice Guys" and your description was very apt for him. He'd make a big show about how he still had manners such as opening doors for women, talk about treating them like queens, etc. It got kind of obnoxious, really cause he'd be going on and on about manners while talking over you anytime you wanted to say anything.
Yeah, show, don't tell. Anytime someone starts going on about the great stuff they themselves do, I start to get a bit suspicious, especially if it seems to be out of context with the rest of the conversation. I think if it's a deep-set part of someone's character, they will just do
stuff, and not find it remarkable enough to mention that often.
Though, as I mentioned earlier, there's also the nice guy who you could see turning into a doormat or being taken advantage of by others--the guy who's always spending his weekends helping friends move or driving them to the airport or stuff like that, with no indication that his friends do anything for him in return. I don't know if that would be considered as "too kind" or in some other category, but that's not a train I want to get on--I don't want to be cast as the bad guy who says, "Bob's always borrowing money and never paying it back, stop lending to him," or "Can't we spend some time together without your friends around?"