I've carried just about everything (except autos and butterflies) and never had an issue. Outside of the greater Seattle area, people are pretty relaxed about knives, and even in the greater Seattle area no one really cares about pocket knives unless you are playing with them in the open.
Autos and butterflies are illegal, but most collectors I know in WA own some, they just don't carry them.
There is a concealed carry length limit which IIRC is 3.5" blade or thereabouts. Most pocket knives with an exposed clip don't qualify as "concealed carry" (the clip is "plain sight") and no police will give you trouble unless you are causing trouble or give the a reason to cause you trouble.
It's really mostly a common sense thing.