No double standards.Only if you ignore the fact that there was women and children among their ranks. Zoro isnt a bad person for murder. But by your logic without knowing the cercumstances of BB's "killings" We auto know he is a bad guy.
Zoro Can kill = Good
BB can kill =\= good
Luffy can break out prisoners for his own advantages = Good
BB can break out prisoners for his own advantages =/= good
Luffy can dream big with crazy schemes beating up anyone in his way = Good
BB can dream big with crazy schemes beating up anyone in his way =/= Good
Luffy can hurt people to take what He wants = Good
BB Can hurt people to take what he wants =/= good.
Really double standards.
1. Blackbeard kill people who did nothing to him, while they weren't innocent per se, they were innocent in that he had no reason to kill them other than he wanted their powers. Blackbeard kills out of selfishness, while Zoro killed because they were planning to kill his friends. Zoro was justified.
2. No said Luffy wasn't bad for doing that. Luffy is a criminal, he's technically an anti-hero.
3/4. No one said Teach was a bad guy for dreaming. Luffy doesn't beat up just any random people. Crocodile, Enel, St. Charloss, Doflamingo, Rob Lucci, Hody Jones, Caesar Clown, that guy in Drum Kingdom, all attacked and were abusing their power over other people. Most of the people Teach killed were done for no other reason other than selfishness. Once again, SH are justified in their beating up of people.
Believe it or not it's not as black and white as you're trying to make it. There are other details about them to consider.