All of mine are looking worn and faded too and some have bits of metal strap on them from when they were part of the railway. I use them as a retaining wall for my fruit and veg garden which would otherwise be a slope and also for raised beds in the ornamental garden at the front. The ones for the veggie patch are lined wiyh black plastic to stop nasties leaching out into the soil and also to keep the sleepers protected from dampness in the soil.
A friend of mine who is a tidy freak painted his with some deeply black, gooey mixture and they look hard and unnatural and stand out more than the plants he has in his garden - all laid out like rows of soldiers and with bare soil between them. My sleepers have faded and are growing a fine crop of moss and lichens. Much more attractive IMHO.