A good window cleaner can be a great resource. A bad one can be a nightmare. Here’s how to tell the difference: Are they experienced? Make sure your window cleaner belongs to an established business and didn’t just buy residential window cleaning supplies last week because they just got fired and decided to try entrepreneurship on for size. And make sure they’re not seasonal either. If it’s their summer job, they probably don’t have the experience you need. Local businesses are usually a good bet. Big franchises with good reviews nationally might be shoddy locally. Are they professional? Window cleaners…