You can get info from the country flag, but you should focus on different things than the actual nickname. Sure some regs might put some advanced poker joke in there, but thats not gonna be many. Hud stats,
sharkscope results, google them at least if they are blocked on sharkscope or country flag, that can give you some info.
And just to be clear, there arent really good/bad or aggressive/tight countries (although
brazil....
) but its mostly about how rich they are. If you are playing higher stakes tournament or cash game and there is someone from western Europe,
canada, Japan, Taiwan... then there is a good chance its a recreational just happily punting around in the $530. If its someone from poorer country, its most likely a reg because recreationals there are playing cheaper tournaments for fun.