Head ons are a part of the game.... Ya gotta live with em. Should a zero be ho'ing a p38? Well... I guess if you want to fine, but it's not a smart choice. Just like trying to HO an A-20 in a P-51. Not a smart idea... You can almost always avoid an HO if you'd like, so don't be complaining about it. If you get killed from HOs, why don't you ask yourself first, why you were HO'ing. Secondly, maybe analyze the previous situation: Maybe the plane overpowered you with his/her guns? Mostly that's the case. Now collisions are a little different. I won't speak on those, but collisions are something that can be avoided most of the time, but those that collide often are those who try to collide often.
Boxboy will probably come in here and state that I am "wrong" about what I have said. It's his opinion. If you have the firepower over the opposing plane, I say why not HO? It's to your advantage!
That's like saying going all in with pocket Aces in Texas Hold'em is wrong in a No Limit game. It's not wrong, it's to his or her advantage given the situation. And that's what HO'ing is like: Poker. It's like saying, here's me and my hand. I'm going all in. You can call it or fold, that's your choice. If you call it, be prepared.