A nice person is a friendly, welcoming, respectful and virtuous person who chooses to always do the good and the right things selflessly without attaching intentions and expectations to their actions.
A self acclaimed nice guy is that guy that tries to pretend he is nice with the intention of getting some gratification for being nice. For every nice thing they do for you, they would attach a sense of entitlement to it, consequently expecting you to return the favour with whatever they want.
A truly nice person never says they are nice and would never rub it on your face just to guilt trip you into doing want they want. They would never say “after doing all that for you, you still go ahead to refuse doing this simple thing for me?”. The above sentence reeks of entitlement and a truly nice person never attaches such to their actions.
A lot of ladies have fallen into the guilt cycle of these kind of guys and have had to do numerous demeaning things just to pay back some “nice things” that was done for them. This is not to say that when someone does something that makes you feel good, you should not reciprocate if you also want to make them feel happy. However, it should be born out of sincere intentions and gratitude and not pressure to return the goodness.
When a self acclaimed nice guy takes you out and buys you food, they want you to also be nice and follow them home. They buy you gifts, they feel entitled to your body. They take you on expensive date, then you must date them. If they give you a ride, you must give them your phone number and if they give you money, then you owe them forever.
If they tell you they are nice, then they are not really that nice, nice people don’t have to say it, it shows in their actions. If they tell you they are just doing it to help you, that is their own way of saying they would require your help sooner and would expect you not to refuse. If they keep concentrating one act of kindness they did for you earlier, then you should avoid accepting a second one.
Finally I am not saying that when someone does all these for you, you should not have a sense of appreciation or show them gratitude if the need arises, after all one good turn deserves another. My point is, you should be able to recognize when someone is being nice to you just to get you to do something for them. This way you can decide to either accept their “nice gestures” or not. Rather than end up with a subtle pressure to want to do their bidding just to return all the “niceness”.