I do carpets, in fact I do a bit of everything pressure washing, gutters, fsg etc.
Anyway with carpets I struggle to see how it beats window cleaning. Certainly at the prices in my area which would be something like 40 first room 3 carpets for 100 etc. I don't think that's bad money but you really need to be getting £100 plus jobs to make it worth while. I can clean 1 room in about an hour or slightly less including unloading and packing up a portable but you have to get there and onto the next job, it's unlikely to be compact!. If I did 3 rooms at 100 then I would expect to be there no longer than 2 hours max that's when it starts to pay.
But the equipment costs more to buy and maintain, it's a constant marketting effort needed.