Well, there are, of course, many wrong ways to vent sex. That's why I don't do it, or knowingly buy from breeders who do.
But, two of these little guys couldn't poo correctly, and they didn't have pasty butt or anything. After further inspection I learned that their little fragile chick bums had been squashed during the squeezing process. They weren't shaped right, and felt wrong when I felt them. The others were fine, but those two chicks, after a couple days of very little successful poo and laboured breathing, died.
After I looked it up, on BYC of course, that's fairly common in vent sexing gone wrong incidences. My friend also had a couple die like this. They're Giant Cochins, and now we're both looking to ad some more to our flock but can't find a different breeder and aren't about to get from her again...
Ok, thanks. Good to know.