Far has got two comparative forms: farther or further. As you can see far is an irregular adjective.
far and far and far
Further and furthest.
The comparative of far may be further or farther.
afar, a good way, a long way, bit, deep, distant, end of rainbow, faraway, far-flung*, far-off, far piece, far-removed, good ways, long, middle of nowhere, miles, outlying, out-of-the-way*, piece, remote, removed, stone's throw, ways
"Litter" is a noun and a verb and, as such, does not have a comparative degree.
smoother is comparative of word smooth.
A comparative for the word ineffectual is more ineffectual.
farther
farther
farther
comparative
Sharper is the comparative form of the word sharp.