execrable
Much scientific literature is impenetrable and execrably written.
I play golf execrably.
He sounds as if he is translating execrably from another language.

SMART Vocabulary: related words and phrases

Serious and unpleasant
abominable
abominably
abysmal
abysmally
apocalyptic
frightful
from hellidiom
fun
ghastliness
Gothically
noxiously
objectionable
objectionably
odious
odiously
unpleasantness
unpretty
unspeakable
unspeakably
unsupportable