I can't see angel's response as it's been deleted although I can guess the gist of it.
Whereabouts in Spain are you thinking of setting up? Problem with having a cleaning business at private homes is that there are many people who do it under the radar. No setting up a company, doing it for friends to start with and then expanding but not declaring any income and you'd be competing with them.
There are a fair few who do do it legally and some of them seem to do very well but you'd have a lot of competition depending on where you intend to move to. The cost of setting yourself up is also very expensive to start and you have to pay (I think) around 250 euro a month social security whether you are earning money or not. Then, of course, there's the licences required to set up a business as you will be autonomo (self employed) and would need someone to complete your tax returns, at least initially and if you intend to have people work for you then that can be very expensive as well.
It's been said many times on here, the only way to leave Spain with a small fortune is to arrive with a large one.
So saying, if you have the experience and can offer a bit more than a mop round and wash the sheets then you may get a bit more business. It may take a while to build up a customer base but, if you are good, word would get around and I know one (legal) company here who does quite well and have expanded into the estate agency business as well.
Best of luck in whatever you do.