There are plenty of 80Plus certified PSUs which are mediocre quality at best.
Show me. With comprehensive load output data.
If a PSU can sustain 100% 12V+ rail load for 30minutes+ and output between 11.4V-12.6V (+/-5%) with 60mV ripple or less (120mV is the max. in ATX spec) then it's considered good in my book.