I dunno about that, Crothian. There's nothing wrong with occasoinally forgetting how a spell works and asking the player to remind you. It saves time, you won't have to look the rule up. Most of my players have not been interested in "winning" at AD&D as much as playing. Good players are an asset to DM's. I'm pretty faimliar with B/X to 2e, but when I'm having a brain fart and player reminds me of how a spell works, I don't think that makes me a bad DM. Besides, I encourage that from players. If I'm wrong on something integral, I'm wrong on something integral.
This is not the same as rules lawyering. And it isn't the same as relying on a player to know the rules. The games I run tend to be 1e AD&D as the sun with 2e AD&D, B/X, Hackmaster, Dragonfist, and The Arcanum in orbit. With all of those various similiar systems smashed together using 1e as default, occasionally I need to be reminded of things. I offer an expansive game with a TON of player options, so if i forget for a second exactly how many 1 hit die monsters are affected by the wizard's sleep spell (that happened yesterday) and I ask, that's pretty forgivable.
If I misunderstood your point, I'm sorry. I'm not trying to be combative.