.TK is probably THE worst TLD. It has a very bad reputation, as you'll find online.
Of course, "Cloud" is a very desirable single-word term to have to the left of the dot.
So the question is which factor outweighs the other.
My hunch is that Cloud.tk is a liability as a brand name. So your buyer would probably have to be some company using "Cloud" as its brand name and obsessed with protecting its brand by buying every single "cloud" domain.
That's just a hunch.