I don't have any sites, but c'mon, this can't be a serious question.
It is better if you aren't going to start out a dark web because you are just going to put yourself in trouble.
There are a lot of hackers and scammers in the dark web.
And you could be a victim or one of it.
There are many dark marketplaces now around this time and the reason is also that Bitcoin is getting more popular so they can also earn now more money. But the bad thing is now that you can buy now easily a gun or something and that is quite bad for all of us.
Does it have a negative effect? Yes, but it's just a biproduct that can't be avoided.
It's better to see the positive effects that come out of using bitcoins in the darknet than the negative effects.