I only recently found out of + being positive and - being negative recently by manually looking up how satellite.earth tagged up/downvotes in it's events. I knew about holding the zap button in amethyst to get to zap settings so out of curiosity, gave holding the react button a try. Lo and behold I can change the reaction options! And + was a heart/- was a thumbs down. Back in the day reddit was my fav so hope such compatibility for voting can be somewhat unified in a few nostr clients. Though till learning of the - reaction, I considered ALL reactions to be positive. After all some dvms will no doubt provided content based on all activity a post gets and you wouldn't help someone providing bad content get more views.