I've never understood why bands do that. If nobody can read your band's logo, how the hell do you become popular or anything? I guess they think they're not brutal enough if the logo can be read or lyrics understood.
Captain Cleanoff (cool sa grind band)
Regurgitation
Broken Torso i think....
Filth
Horde of Worms
Goratory i think...?!?!
Beheaded i think.. (ive got thier album around here sumwhere so i should know)
vile
MISCREATION!!!
MYOPIA!!
ahhh dunno the next one
SPAWN OF POSSESSION!! (technical as fuck swedish death)
The trend was around in the early 90s though. I might have gone into Extreme Aggression (death metal shop in Melbourne) a bit more if the stuff they stocked had decipherable covers!