Cops can arrest you for any reason/no reason BUT then they open themselves up to lawsuits. So generally they do not do that.
This is why it's always best to be professional and comply. You need to "fight" in court, never the street.
For the guy making the comment about beating an unarmed black guy, I hate to break it to you, but it doesn't matter if a person is armed. If they are resisting, use of force is allowed. UOF needs to be proportional however. A guy struggling can't be shot in the head for example. But if they are trying to grab a gun (real or perceived) now they became a potential deadly threat and lethal force can be used.
The vast majority of these claimed "police excessive force" cases are in fact the fault of the "victim". They choose to not comply/fight, but then they get their ass kicked or killed and all the sudden it's racism.
Sorry, no.
You don't have to comply - but if you fight and get roughed up you brought it on yourself.
Now back on topic. The beauty of AMPS is they offer a legit service. They are a "licensed" business usually. Who cares what cops say, we know you did it, you are here for XYZ. Response... that's not true, I only came for a massage, no idea what you're talking about. I don't want to discuss anymore until I have spoken with counsel, thank you. The end.
If you stick to this... and it can be hard, as they will try to pressure/manipulate you (but see through it) you will 99.9% be fine.
Also, don't be an idiot like Robert Blake. Cops use hidden microphones. So if for example they detain you, cuff you and put you in the car for a bit (another scare tactic) don't be talking to yourself outloud saying crap like "Dammit I can't believe they almost caught me doing XYZ here!!" - More often than not, people sink their own ship.
Don't be that guy.