I find dead pixels to be 'annoying' but even worse than them are flashing pixels.
I had a Digimate 17" TFT which had a single flashing pixel and try as I might my eyes were constantly being attracted to it flashing away in the corner of the screen. As it was the 'only' defect of the TFT it was well within the ISO regs and so no exchange or refund was possible.
I would not feel confident with dealing with a retailer who offer a dead pixel check and then buying a TFT from them without having that check done. I imagine that when they have tested a TFT for a customer who has ordered such a check, and then find one flashing, they are still going to sell it on to someone else as it could still be within the ISO regulations of a Class II monitor.
My Samsung 22" pebble had a stuck pixel, it was stuck on red, but with a bit of pressure, using a cotton wool type stick, it started working fine.
I am looking at the 24" TFT's but the dead pixel lottery fills me with a little dread.