I guess that most people visit forums when they have a problem or something to complain about. This paints a very subjective picture of what percentage of users may have received faulty units.
No one is going to register here to let us know his screen is OK. So I guess when 10 people register to complain, there are at least 10.000 other people who have no problem at all.
So statements like "you're lucky if your screen is OK" are total rubbish in my holy opinion.
I respect your opinion but usually, monitor reported problems follow "iceberg theory"....I mean customers announce in the forums only a small part of "the" problem...many computer customers don't read/write in forums or don't care about monitor problems because they replace iMac under warranty 2-3 times until they get a good one (nice prospect?) or prioritize i.e. IR monitor problem as "minor" or "LCD inherent problem".
Luck is a serious factor when poor QC exists...