Huh, I would venture to say it means about the same as when people say a *horse* for sale is "easy to catch", "sound", "quiet", etc.... which is to say, it means whatever they want it to mean. Even if they are quite sincere, some sellers have, um, a different relationship with consensus reality than the rest of us do
I would place no credence in those sorts of claims whatsoever. Go see the goat, either you get on well with it or you don't
(edited to add: with horses, dunno bout goats, the phrase "catches easily" [that exact wording] is occasionally used to describe a mare that gets pregnant easily i.e does not have to be rebred in a bunch of successive cycles to get her in foal)
JME (with horses, not with goats specifically but I can't imagine goat sellers are any different than horse or other livestock selles),
Pat