I have seen horses crib on anything and everything with or without a collar. Even saw one hook his top teeth on the top wire of a fence (mind you it was barbed) and go at it. One I know will hook his teeth on a lead rope when standing tied and crib....with a collar on. Then there are other cribbers that don't do a bit of cribbing with a collar on, but take it off and immediately they are looking to go hook their teeth on something and crib.
It is like anything with a horse. There is no perfect horse, so you have to make a decision if you can deal with the issues that the horse has. Some horses have minor things, while others have more major things like cribbing. I do consider it a major thing because of the potiential health issues. Turn out does help a whole bunch, but it isn't always the answer. Like someone said, that it can run in a bloodline and it can also come from being stalled. I personally think it is temperment which is also in a bloodline. If the horse fits you or is a highly trained horse you can compete on, then it may be a future mount for you. If it is a project horse that you would have to really work a lot on or spend a lot with a trainer, I say pass it up and look further.