I do both - what got me into it was I used to clean the windows of a carpet cleaner who used to go out at 9am and be back for dinner at 1pm with £150 plus in his pocket , me I had just done a few houses more up his street and earned about £60
I tagged along with him for a while for free and he showed me the roaps as it were , and went on a few courses , got a good machine ( you need to spend aproxx £2000 on a new one) and off i went .
Ive now got a nice 50/50 split with both , I dont need to spend lots on the advertising as I have the windows to fall back on - unlike the stand alone carpet cleaners .
also the cost of the chemicals to clean the carpets etc is pretty cheap per job once you have paid for the machine. - less than resin,water etc on wfp I think .
In my view its the best thing I did to earn more money - well apart from uvpc cleaning that is