It was obvious that the masked liberal protesters at Berkeley were there to start trouble, why did police just stand around and let them?

The police were obviously following "stand down" orders. Rest assured, if the protesters were masked conservatives demonstrating against democrat hate speech. They would have been jailed and it would be on the news for weeks. Every known conservative would have been called on to condemn their actions. Some people here lied and said those protesters were conservatives. I'll guarantee none voted for President Trump.

answer

I don't care much for protesters. Of either side or of any party.

They were paid alright by hilary & her buddy obammay

those weren't liberals. they were anarchists.

Those were paid conservative agent-provocateurs. Liberals practice non-violence.