Is the glass of an LCD screen water proof (ignoring the electronics that power it, just the external glass of the thin LCD unit, or can water seep though the metal edge bonding round the LCD unit????
Are we talking waterproof or Moisture proof Rusty?
Waterproof, I'd say no way.
Moisture Proof, possibley but obviously would depend on how damp/warm the atmosphere. I would imagine a large well ventilated bathroom, for example, would be OK although it could succumb over time.
Has it been splashed or have you still to try the splash test?
I'd say best avoid water where possible - if that's not possible there are Point of Sale type LCD's for use in pubs and the like if you think your displays going to take a bath on a regular basis.
We use these models if you want a decent image in a 'harsh' environment - though they are pretty expensive.