I think that the thing with window cleaning is it's so damned easy to get in to.
I mean if you think about it how many businesses require an outlay of around £100 and allow you to earn from day 1 with no training whatsoever?
So while it's great for us full time "pros" to charge £25, £30, £50 per hour we need to be mindful and look over our shoulders for the guy(s) who could pop up and do it for half that.
I like to think my long-term customers are loyal but I reckon their loyalty would be sorely tested if someone came along and said "He's charging £25?...I'll do it for £10...at least give me a try."
It's not the old geezers who want to earn a bit of summer beer money that are the threat. The threat comes from people who are financially settled with little or no mortgage, still want to earn but don't need to earn bundles. They can undercut you every time simply because their financial needs are less than yours.
With wfp there's a fair amount of initial outlay, but with trad there's as good as none.
I'm a prime example: 4 years ago I went to B&Q and bought ladders and a bucket. Went to the pro shop along the road and bought a squeegie...total outlay around £120. Having never ever cleaned a window in my life and having no customers earnt £130 in week 2....great for somebody who was until then getting £50 a week job seekers allowance
OK I've now seen the light and realize I can charge more...but back then God only knows how many w/cer's I UNdeliberately undercut!