Here is what I have experienced:
You play people better than you, you like playing them because it helps you get better and it helps their ego and confidence by running you like a dog, hence they feel like they "own" you.
They(the better people you were playing) think because they have beaten you so many times think that their overall record against you will get them through matches against you just because they have beaten you so many times, hence, they are "supposed" to beat you. If you push them.... they will play with you just to prove to themselves it was a fluke or that they were having an "off" day when you took them to 3 sets when normally they beat you in straights, something like 6-2 6-3.... or something like that.
You play with people lower than you, because YOU AREN'T THE TYPICAL CLUB *****. You will play with most anyone....anywhere....anytime, because you love the game.
At some point in time, if you keep playing people lower than you, and they keep getting better, will one day beat you. Then you play a few more times and it's win some lose some. That lower person will walk away from you, thinking they are now better than you and they will no longer play with you because they think that "you" are now holding them and their game back.
And the cycle continues over and over......
The great thing about tennis is that you get to meet alot of people. Bad thing is they are the type of relationships that are here today, and gone tomorrow.
I'm assuming you're a nice person. Now if you're constantly trash talking and strut'n around....making obviously bad line calls....then that might be your answer.
I've had people say to me: "Why are you playing with them; they're terrible". In my mind I'm saying: "Because I'm not an effin' *****, like you, and I like mixing things up and meeting new people.
I will say I get those "stuck up *****" thoughts every now and then, but then I just remind myself that that is not who I want to be, so I will usually hit with anyone, given they can put a ball over the net decently.