I don't think that Democrats should get too hung up on the word "weird" specifically, because that can get overdone pretty quickly, but the general strategy of gently insulting Trump in a way that flusters him and embarrasses his supporters is golden imo.

I'm in a terminally red area. I usually try to avoid political discussions, but when I've been pressed for my opinion on Trump, I tend to avoid talking about policy, because really, that's a dead end for the type of person that would start this conversation. Instead I'll respond with something like "politics aside, he honestly comes across as kinda dumb" or "Naw, he creeps me out". Bam! There isn't a fox news talking point for that that doesn't involve trying to change the conversation to some dem, and really these statements are just a matter of opinion. Go straight to policy and you'll get memorized talking points back, go to really harsh direct insults, they'll dismiss you as having TDS. But when you keep it subtle and insulting in an everyday, almost dismissive sort of way, like by saying say "sorry no, your guy is just too plain weird", that gets to them. It forces introspection, and though it might not mean anything that day, those short moments of realizing that their politicians really are a bizarre group might start to add up. I know it did for me. Antagonizing Trump should be secondary to subtley and carefully making his supporters embarrassed to support him and dorks like him.