You will get more leads if you offer window cleaning but I would not bother with just carpet cleaning. I had a lad who used to work for me who could clean windows as well so I told them they may as well give me window cleaning leads too. I got none for carpet cleaning but a few for windows. The thing is though that when you dig deeper you find out that the way they got these leads was to just to tell them that we would be passing them anyway and we would nip in to quote so they where poor quality leads too. They already had window cleaners anyway so were just using me to see if they were being charged to much. I was thinking of going into commercial window cleaning at the time as i had 2 lads who could do it but tbh i was absolutely stunned at how low window cleaners where charging commercial customers which was peanuts so never bothered with it. Also they are southern based with strong southern accents so I would not even contemplate it if you are northern based and for just carpet cleaning is waste of time and money from mine and others experience.