I've only had good experiences with the local police here in San Diego when it comes to knives.
The last experience, just to recount one of many- A pair of cops in an SUV pulled me over on my bike, the senior cop said he stopped me because my license plate wasn't mounted properly. I was openly carrying a fixed-blade on my hip (knife pictured below), he told me that he was going to take it for their own safety just for the duration of the stop. He pulled it from the sheath, and placed in on a patch of grass a few yards away.
He asked me why I carried it, I said "To cut things". I said "To my knowledge it's legal to carry as long as it's visible ", he said that was correct (I said that just to let him know that I knew the law). He asked if I had any other weapons on me, I said "No. But I have a few folding knives in my jacket", but he had no interest in those. He didn't ask if he could search me or my bike, nor did he compel a search.
He took my drivers license, checked me out on the computer in his car. I was clean. So he said he was letting me go with a warning and instructed me to remount my license plate. I agreed. He instructed me to wait until they were back in their vehicle before I retrieved my knife, which I did.
He was a complete professional throughout the experience. Polite, no attitude, no snide comments or insinuations about the knife or why I was carrying it. And I was polite to him. I know better than to give cops attitude, not that I ever would.
I would also add that I'm a biker. So the fact that he didn't give me a hard time about being a biker carrying a fixed-blade on my hip, and let me go with no citations, shows just how chill he was, and how unconcerned he was about me carrying a knife. I suspected that he was just using me as a training stop for the second cop, as the second cop looked like he was fresh out of high school.
I don't worry about the cops. I know the knife laws of my state/county/city, I know my rights. And I've been arrested before, been to jail, been through the courts, been to prison, so I know how the system works. As long as I know I'm legal, and I am, I don't worry about the possibility of an unlawful arrest.
However, I do agree with not carrying anything expensive or a prized possession, why tempt fate. There is always the possibility or running across a bad cop.