I just made a post about this a couple days ago: nostr:note1ka3pp0gc83cflnnhd58j3pehnk5z8g6f4evd4hjjtgcpvwkmwj2qjqp7w2
Using noStrudel, it will show you the status of every event generated from your account. I've started noticing that with any event whether it be a reaction, zap, note, etc. just as you mentioned, there's always at least a few relays that don't accept it for one vague reason or another.
The thing that really bothers me about it is that with most of them you can't go and see what rule you broke or what the specific cause was if they don't include it in the 5-6 word error.