i know a few guys who are doing fantastic at just window cleaning, stick to what you know and put all your energies into growing your business.
don't understand why people want to add new strings to there bow without taking on staff to cover the extra work, if your not busy enough doing what your doing, then your doing it wrong and no amount of diversity will make up for it, while your putting your efforts into carpet cleaning, your window cleaning will decline and you'll be back to square one.
just my opinion, not having a go.
derek