I'm also in the Los Angeles area. I used to have one side of my radio parked on 146.520 and we used to enjoy some pleasant short QSO's or move off the frequency if we decided to talk longer. About 18 months ago the guy down by Knott's Berry Farm showed up and he's been a constant source of annoyance since. He can also get quite argumentative if he doesn't like your tone. Sounds like a lot of 12oz courage to me. The other guy, used to be on several local repeaters and constantly asked for radio checks. When you would answer him he would disappear, only to reappear ten minutes later to ask for a radio check again.
Unfortunately, ham radio operators are a reflection of our society. I get the impression that Mr. Farm is probably living on disability with nothing better to do all day and Mr. Saigon likely has some "challenges." Add to all this the fact that I also hear APRS bursts and the occasional people that think it's cleaver to do simplex on DMR, P25, D-Star or whatever and basically 146.520 has become the Channel 19 of today.
The group I hang out with have picked another simplex frequency that we all hang out on, but it's kind of sad. The old days of talking to new people seems to be going away and its being replaced by a plethora of the prepper, survivalist, off-road crowd, or boot leggers operating illegally. We have a bunch of Spanish speaking workers on 146.490 near me that seem to be working at the rail yards. Someone dialed up some radios for them and they likely have no idea what frequency they're on. I have lost faith in the FCC to do anything except collect fees and make questionable rulings. On the rare occasion that they actually do issue a fine, it seems it is more often than not, not collected and the offender just keeps on keeping on.
Fire up the Zello!