The majority of instances defederated from hexbear and lemmygrad.
I think if you have an account on such an instance you'll never see anyone or anything from them (correct me if I'm wrong).
If your own instance is not defederated from them, then you may see the odd hexbear or lemmygrad user or community, but since most instances have defederated from them, that also means that the communities hosted there won't have hexbear or lemmygrad users in them.
Likewise, if you are not defederated from them, and find a community hosted by an instance that is also not defederated from them, you will almost certainly see troll comments from hexbear or lemmygrad.
I hope that's somewhat clear.