-Litmus test. How to know a player is lame:
Player discovers Option A (with x flavor) is objectively, mechanically, more powerful than Option B (with y flavor--totally different).
Player chooses Option A, doesn't see why you wouldn't.
Player is not 12 years old
At my regular game I fall prey to this mindset, that being the one belonging to the ruthless min-maxer. Our group has a couple min-maxers and I feel the pressure to go with the group. We're playing 2nd Edition Skills & Powers, possibly the most convoluted set of rules since 3e. That makes sense somehow. The more I get into the OSR stuff the more the endless lists of options and points and traits and disadvantages and bonuses and abilities oh my annoys the crap out of me. Yet when creating my character for our most recent game, I took the extra rolls the DM offered, squeezed every last drop of ability out of those scores, and min-maxed my character for the ultimate potential in being awesome at table, for fear of having a dumb character who can't do anything interesting in comparison to the min-maxed PCs of my fellows.
I dislike myself for falling prey to this again and again. Each time I make a character I try to make an interesting one, not just one who can do stuff like 'OMG did you *see* that?!' You don't need to be the most awesome to make a memorable and/or enjoyable experience. I do know this. I fall prey to peer pressure, even of the unspoken kind. If everyone at table is wearing a purple hat and you insist on wearing a pink one, you're going to stand out. Now, these people are my friends and no one is going to yell at me for not min-maxing. But I fear I will have a sub-par experience if I don't min-max like the others do.
I once made a kobold priestess who was originally intended to be a kind of comic relief. I was going to play her for her personality, not for her ability to be the damned medic (side note: I hate being the medic. Clerics do not always have to be the medic. Probably why my last cleric was an evil specialty priest of the god of storms. I didn't have to feel obligated to heal the party - my character looked out for herself first!). The first version I rolled up, well before I was ready to switch characters, had a slightly above-average Wisdom. By the time I was ready to run the character, I had re-rolled her and given her an 18 Wisdom. Why? Because I have to be GOOD at stuff! Everybody else at table is GOOD at stuff! If I'm not I'll look lame and suck and I won't have fun. That's what I probably thought at the time.
I suppose I'll just have to take the plunge one day: make a character as if I'm playing in a good old B/X or Advanced game and try my best to have fun with it. I've considered bringing back the kobold priestess, but I still don't want to play the cleric. Maybe a kobold thief... I like the idea of being this scuzzy little reptile who speaks broken Common, eats rats, and doesn't comprehend the strange concept called 'bath'. I could do the same kind of thing with a more standard race, but in S&P there are a heap of race choices, so why not play the critter I like the most? And most importantly, why do I feel this need to munchkinly min-max?