Technically dead pixels are pixels that just won't light up anymore. As in they are black. Any other pixel malady is considered a "stuck" or "locked" pixel, meaning it is stuck on a particular color - usually white or red. I'm not really sure why these are the most common stuck colors, but they are.
A single stuck pixel on a 19" monitor probably won't be very noticeable, but it isn't clear to me whether it's just one pixel or several (singular vs plural is difficult to decipher in that quote). Pixel defects in LCD monitors has dropped considerably in the last 18 months, with "tolerable rates" coming down from 5-10 dead pixels before the manufacturer will take it back to 1-3 dead pixels. I'm assuming it's just one red pixel in this case.
I would be cautious in a case like this. While that monitor is unlikely to ever develop another dead or stuck pixel in the next several years, LCD monitors have dropped in price enough to make me think twice about buying a used one. After all, of all the parts that go into making a computer, the monitor is the single most important part for the user. A bad display can make your user experience miserable. And since you have to stare at it for what could very well be several upgrade cycles, it's important to be very stringent in how you choose your display. That's just my two cents.