Indeed. I don't see anything posted that I'd consider "incorrect" or bad info.. but some of it is open to fudging by opinion. Example: I would disagree with RetroTechie that laptop pulls are not worth the risk/hassle. I think many times they are if you are looking for unprotected cells. Yes, there are dangers. Accidental shorting of the battery pack while disassembling is a very real danger. I've come close myself with a few sparks off of the circuit board.
But after tearing apart a little more than half a dozen laptop batteries, I have 42 fully functional, unprotected 18650's with 2000+mAh capacity. All LG, Sony, or Panasonic cells. I also have new, protected 3100mAh Panny's I've purchased, but that's different. The laptop pulled cells work great in all of my single cell lights (which is all but one).
That being said: I have had about an 80-85% success rate with those. The ones that come back up to voltage and have decent capacity were all at 2.7 ish volts or higher. I've recovered some as low as 2.3, 2.4 or so. But that was rare and maybe a bit lucky.
So to answer the original query, I would toss cells that no longer charge, heat up excessively during charge/discharge, lose their voltage in storage over a short period of time, drop below 60% of original capacity, or have physical damage beyond torn wrappers. But that's just me.