Yeah, Rose nailed it as far as I see it.
I've had a few partners who were, as I like to put it, "less than compatible" with me as far as sexual activity goes. Some were even long-term relationships. The biggest key in what was going wrong in those interactions, from what I've gathered, was a lack of communication or just poor communication which resulted in one or both of us not being sexually satisfied. Going through the motions, not openly sharing or seeking what we wanted, not trying to learn, etc.
Sex is like a conversation. If you're speaking the same language, open-minded and are extremely compatible, words don't even need to be spoken (but they sure as fuck help, especially in trying new things), but if there are misunderstandings or there is a lack of information, it tends to not really go that well. Things get awkward, comfort level diminishes, the fun just dissipates because the connection just isn't there.
Big point being that, in my opinion, there isn't necessarily a direct correlation between "experience" and "good or bad" since every partner is different. It's all about what kind of connection, chemistry and level of communication is open between those involved.
...that's just my two cents based on my personal experiences.