Let me save you the trouble of further reductionism or veiled insults: I don't like the kind of gameplay evil PC's get up to, I don't like putting myself in a position of arbitrating it, and I don't allow it. If you think that makes me a lesser DM, I won't lose any sleep over it.
It's the people you've played with that causes this.
I guarantee you could DM for my evil characters. Because my "evil" characters are up to exactly the same things the rest of the party is. It's just their reasoning for doing them that differs. And they might not have any qualms about getting their hands dirty concerning things like goblin babies....
For ex I give you Bob, my 1e NE Deep Gnome;
1) He's "evil" primarily because the rules don't allow me to be a fighter/ASSASSIN who's alignment is anything but evil. It's a rules thing. And the DM won't alter it. So. If it were up to me I'd describe him as Neutral-GREEDY.
He's an assassin not because he accepts $ to kill people as a job, but because that's the skill set that absolutely best fits the character I envision. Before joining the surface dwellers as a guide, he served as a long range recon scout for his clan. (character was brought in as a replacement character after my Paladin died unrecoverably) Deep Gnomes live in the underdark. You don't survive solo in the underdark without mastering some brutal skills. He's got no problem stepping out of the shadows & sticking a pick axe in just the right spot to drop a foe in 1 hit (roll on the assassination % table). Or killing things 1st & then asking questions.
2) He really doesn't care either way about the party. Or for their stated reason for being down here in the underdark. Except the 1/2ling. He likes the 1/2ling. (more importantly his sister likes the 1/2ling). And after two months of adventuring with these surface dwellers he's certain they are STUPID. They're GOING to get killed down here. He'd wash his hands of these fools - but holy crap, the loot being gained is INCREDIBLE! (Deep Gnomes are stated in that edition as being willing to go to considerable risks for gems. Working with this party certainly qualifies
)
The party might be stupid surface dwellers, but they are really effective at killing things the Deep Gnomes wouldn't mind seeing exterminated. And so he plots the best way to avoid a (complete) TPK & haul 50x his own body weight in loot away....
3) Looking at the G/N/E alignment description:
Good doesn't fit.
Neutral is pretty close.
Evil? Well, he really is helping the party murder a city full of Koa-toans (and mindflayers & Derro, &......) for his own gain. Sure, he has no problem working with others - his clan, the party, etc. Nor does he have any real plans/intent of betrayal to any of them. And wiping out these threats is certainly a worthy cause & a boon to all. But really he's doing it to get rich. And he's not willing to die for the party.... So I could see it if you wanted to call him evil.
*like I said though, it's really just a rules thing. To get the Assassin abilities in 1e I had to make him evil. Even though I think Neutral is the better description.
At the end of any given session do you know what my "evil" character has done? Cheerfully murdered & looted Koa-Toans/Derro/Mindflayers, etc - right alongside the GOOD ranger, 2 GOOD clerics, and a mixed lot of other non-evils.
Oh, and every now & then I'll cheat the Ranger at gambling/cards during downtime.
