It doesn't fully demonstrate the issues with toxic clans, but I'm hoping this helps you consider which clans you join. When I flew past, they started blaming me of spying, which led me to leave the clan.
The leader and a few of their friends were talking about some drama, and I wasn't paying attention. When I was in one of the more competitive clans, I was doing questing at Scuttleclaw Island. (Boring and poorly written personal story, but it might help you consider you options) Players who don't have trophies but promised to earn lots.
Players who are around because of their trophies
(They don't really talk to lower members) I noticed that the social dynamics in many other Top Clans involve something like this: Somewhat unrelated stuff that I wanted to add: It's a good place to build confidence before going to a more competitive clan. The leaders are really friendly and we have quite a few clan traditions like skydancing and racing after battles, and skydiving. We don't care about trophies(as our leader has 15, so we can't even have a limit). My current clan, Z War Clan, is a good option.
I've been in one of the clans about rank 50, and it plain freaked me out how trophy oriented they were. Sadly, most of the Top Clans(I believe you are talking about above 100th place) are competitive.