I have been thinking about this, and it occurs to me that perhaps this isn't a BAD breeder, but an inexperienced one. A lot of temperament is genetic, it could be that if the breeder has limited experience with only a few birds, that they have noticed that THIER pineapples are sweeter than THIER other GCCs. When I worked on a ranch we could tell within minutes if not under a minute whether a colt had been sired by one of our studs or if the mare had been pregnant when purchased. This did not have to do with breed, they were all the same breed, but our horses were bred specifically for temperament and it was obvious. It could be that the pineapples that particular breeder produces are genetically inclined toward better temperaments than say, the turquoises they produce.
I think of my cockatiels. I only have two pair, but IN GENERAL on pair produces incredibly clever, quick developing, excellent flying, super smart babies while the other produces super cuddly, over the top mushy, love-you-till-you-die babies. All th babies are smart, and all are sweet, and all are cockatiels (tons of colors, no way to determine it by color, like I said), but the lines have different characteristics. I know you said you weren't going to buy from them, but my first answer was pretty harsh and I have been thinking about it andwanted to clarify that the breeder could be going off their own observations and simply not have enough data, rather than just being a bad breeder.