Changing the appearances of characters

You can change virtually everything via the boulder, dungeon, effects, graphics, monsters, objects and warnings settings -- add the fact you can edit the source and the only limit becomes yourself... and the ASCII charset. That's being addressed in UnNetHack, however.

If you're playing online, however, you shouldn't change these settings or viewers will be confused. If you aren't, you should totally try it!

Changing ghosts and shades to 8 and golems to 7 is popular. By default, ghosts are represented by a space, which makes them nearly impossible to see. Golems aren't quite as bad, but it is a bit difficult to pick out a ' walking around.

I wouldn't worry too much about confusing people watching your game online; many of the best players on NAO use these settings and people viewing games regularly will be familiar with them.