Turbid, muddy, roily are comparable when they mean not clear or translucent but clouded with or as if with sediment.
Turbid describes something (as a liquid or, in extended use, an idea, affair, or feeling) which is stirred up and disturbed so that it is made opaque or becomes obscured or confused.
Muddy describes something which is turbid or opaque as a result of being mixed with mud or with something suggestive of mud or which is merely mud-colored. In extended use the term carries a stronger suggestion than turbid of a dull, heavy, or muddled character.
Roily describes something which is turbid and agitated.