It depends on the brand and size of the LCD monitor:
Brand -- Different companies have different policies with regards to how many dead or "stuck" pixels they will allow before giving you a replacement monitor. Some companies, like Planar, for example, have excellent policies -- anything more than 2 stuck or dead pixels on a 20" LCD and they'll replace it! That's outstanding. Other companies, like Viewsonic, for example, allow up to 10 dead or stuck pixels before they'll replace it for you. (These specs were as of about six or eight months ago when I was monitor shoppping -- I haven't checked since then, so they may or may not still be accurate.) And you guessed it -- the monitors that can have more dead or stuck pixels tend to cost less than the ones with more stringent quality control. The companies claim that the more panels they reject on the factory floor due to too many defective pixels, the more they have to charge on the ones that do pass the test (to recoup their losses). Probably some truth to this.
Size -- The bigger the monitor, the more pixel elements it has and thus the more possibilities for dead or stuck ones. It's very challenging to make, say, a 20" or 21" LCD panel with zero bad pixels. From what I hear and read, most industry people consider 1-3 bad pixels pretty darn good. Apple's policy used to be, if memory serves, that they'd replace a 21" Cinema Display if it had more than 5 bad pixels. Haven't checked their policy lately though. I didn't really research monitors smaller than 20" and 21", so I can't really comment on them.
Once in a while you find folks who get really lucky and get an LCD with no bad pixels, but it's not the norm. Expect to have a few. What I'm gonna do if/when I ever decide to get an LCD (I went CRT this time) is open it up right there in the store, plug it in, and check it before I buy it. Oh, and sometimes if the bad pixels are off to the side or in the corners, they're less objectionable. It's when they're near the center of the screen that they can get really annoying.
There you go -- brief primer on LCDs & bad pixels.
