If your pcv is clogged which is the only way they go bad, then you will have oil leaks somewhere on the block. Back in the day they had breather tubes coming right from valve covers. Now they want you to take what used to go through breather tubes to do a second burn. Without breather tube or pcv, your gaskets will leak, no way around it, and generally why valve cover gaskets are torqued lower the head gaskets. You would rather have that gasket fail, but when they fail it causes more issues and there is not only a release of pressure but often a vacuum as well, meaning debris can go into the engine. My guess is 9 times out of 10 you would have leaky valve covers if your pcv failed, probably the first sign would be those leaking onto pipes and burning which would alert you to the issue.
