I have talked to a few breeders who basically report the same thing, once you got a no to low kink trend going hang onto it. Last time I talked to brian from bhb he said he hatched over 50 caramels in a row with no kinks and some of those caramels came from female caramels that had no slugs. It does appear a few have selectively bred it out or at the very least reduced it significantly.
Me on the other hand, I like the ultras looks better, so I'll dive into them when I feel the time is right.