Hi there,
You heard "half-right". Yes, soap can damage the anti-glare/static coating. So can alcohol...and I'm not talking about accidently spilling a beer on your monitor (uh, that would be bad though!). I'm talking about those "anti-static wipes" that you can buy. They have alcohol in them, don't use them. The best thing to use is a dry, clean towel. I wipe my screen once a week, to keep the dust buildup to a minimum. If for some reason you get spots on the screen, (usually spit, from yelling out loud after getting fragged into a million pieces in my case) use a slightly moistened as in barely damp clean towel.
My old monitor (Dell, excellent 17" unit BTW) had a regular CRT as opposed to the FD Trinitron. I used the alcohol wipes on it for two years with no discoloration or ill effects. My Micron MX900 (Sony FD tube) came with a big (two feet by one foot...no joke) yellow piece of paper taped to the top of it distinctly and in very definite language telling you NOT UNDER ANY CIRCUMSTANCES to use any kind of alcohol or caustic cleaner (they're talking about Fantastik/409 type stuff) on the screen because the anti-glare/static coating could be damaged. I doubt that just a few applications would hurt anything, but why chance it? Dry or slightly damp towel. That's the only way to go. Oh yeah, vacuum the top and sides of it every month to prevent dust buildup too.