My favorite dictionaries show "wants doing" as equivalent to "needs to be done." Online Collins Dictionary web site 5. VERB [no cont, no passive] If you say that something wants doing, you think that it needs to be done. [mainly British, informal] The windows wanted cleaning. [V -ing] Her hair wants cutting. [VERB verb-ing] New Oxford American Dictionary 2 [with infinitive] informal ought, should, or need to do something: you don't want to believe everything you hear. • [with present participle] mainly British (of a thing) require to be attended to in a specified way: the wheel wants greasing.

It is absolutely correct and makes good sense. You can want any noun, and "doing", as a gerund, acts as a noun. You can want "doing" just as well as you can want "chocolate". It is not a common thing to say, but don't let that stop you from saying it. Here's an example: "Those dishes want doing" could be spoken in place of "those dishes need to be washed".

Yes it most definitely exists. It means needs doing needs to be done. Most commonly phrase is "it wants doing" or you can use the "want doing" like has beeb shown. ignore those who say it does not exists. Current and actual true example relating to myself and my home. "My floor wants doing, after the mess I made repairing the wall in the lounge" = means I just repaired a hole in the lounge wall and now the floor needs sweeping and mopping/cleaning.

"Want doing" does not exist. You could say "want to do" or "want to be doing" depending on the context. Hope this helps!

-- What do you want? -- I want trees and flowers arounds, birds singing and the spring wind. As we have "a want a pen" structure, we can easily make "a want swimming in the sea".