Cool! Was he building embedded testers, or commercial testers for semiconductor vendors? I would imagine that a lot has changed since then, especially with the shrinking process size and corresponding increase in retention failures.
In my experience, most of the reputable vendors like Micron, Samsung, and Spansion are pretty up front with how many bad blocks they allow their devices to ship with. The Micron device I've worked with most in designs allows 80 bad blocks per unit at shipment - that's about 2% of total blocks. I've never seen a brand new chip with that many bad blocks straight off the bat. (Two bad blocks in a brand new chip is unusual.)
Most of the big vendors moving to support the ONFI standard has actually had a pretty interesting effect - since NAND is in such demand and has a common interface, it's become pretty commoditized. If you want to sell chips, you have to abide by ONFI. If you do that, and your prices are competitive, your products have been just about guaranteed to sell. As a rule of thumb, however, I would agree with your sentiment. Vendors who won't share raw bit error rates or uncorrectable bit error rates are generally not worth the time of day. That's part of the reason I'm so fond of Micron and have cited them a bunch in these articles - they are very forthcoming with data about how their parts work, and how to put them into systems in such a way that they'll work over your device lifetime.