I guess for each person, what makes a partner good or bad in bed is different, but for me a good partner is one who is having fun and realizes it is a recreation to be enjoyed. Sex begins before you ever get into the bedroom, that is just where things get finalized.
Probably the best lover I ever had was my last GF, we were both in our 50's, and she was FUN ! She initiated sex, was very playful, knew how to tease, and was open to a lot of exploration. I kept telling her I could have really used her when I was 18 !
We had sex pretty much daily and in various places and in various ways. She never made me feel weird about suggesting something, and she would bring home toys for us to try together. She told me often how much she loved our sexlife together..........and that is always nice to hear.
But mainly it was the little things she would do, like we would be sitting at a bar or restaurant and she would say "Ooops, Honey, I forgot to wear my panties !" ...and she would give me a little peek !
THAT will get your attention every time ! Even watching TV was an adventure because after a while of sitting together her hands would be roaming, and she would get this little look on her face that let me know she was in the mood. Sometimes while I was driving she would be "exploring" me, or sometimes herself. It was nice as a man to not have to always be the aggressor.
So, playfulness, acceptance, a healthy sex drive, and a little exhibitionism thrown into the mix make a good lover IMO. Now that I think about it, I really miss her !
Don