There are some people you roll with who are focused on getting it right; they’re the technical guys and girls who’ll push you, but you always feel like you’re getting something out of it. If you’re training, they’ll be good training partners and if you’re competing they’ll fight hard but cleanly.
And then there are those who are more interested in winning every roll at all costs. When you train with them, there’ll be thumbs in eyes, flailing elbows, fingers bent backwards. Any time they feel vaguely threatened, they’ll go mental and do their best to drop you on your head. They’re not usually terribly effective – at least, not against anyone good (although they’ll be the first to tell you about who they’ve tapped in training) because they never put their ego to one side long enough to actually learn anything. But even when you win, you come away with bruises and niggly injuries, feeling like you’ve just wasted 5 minutes of your life that you’ll never get back.
Dealing with people in general seems much the same; attitudes towards personal and professional relationships seem to fall into the same two categories. Life is much better when you pick your sparring partners carefully.