People on here have focused in on bird poo and fly poo...as if every house you come across has every window covered in the stuff!
In the past when I was wholly trad I thought I always did a perfect job....absolutely mint!
Until the customer asks you to clean the insides for them...
You will almost certainly come across the odd mark, kick, line or run that you need to nip back out to get rid of.
Is bird poo really that much of a problem with WFP? Not in my own opinion anyway, most of the time you can see it and get rid of it without any problem at all.
Seagull poo is probably the worst though, and I'll agree you can have real problems with that on upstairs windows.
But again, most window cleaners are not going to have to deal with this day in and day out are they.
Fly poo, spider poo and bee poo, they call all be a pain to get rid of no matter the system you use, especially on frames and sills, but where spiders and there nests and webs are concerned, WFP rules, you can blast them out of every nook and cranny, frames can be cleaned far more intensively with WFP.
With some of the insect marks the only way you will get rid of them, of frames especially is with a lot of elbow grease and a cream cleaner....so sod that for a game of soldiers, trad or WFP I'd never go that far unless the customer was prepared to pay a lot extra for the service.
I do plenty of houses inside and out, ditto with a lot of commercial work, and although the work on the outside may not be inch perfect all the way around, nothing is usually bad enough to stand out, and if it is, just as I would when I found such mistakes when working trad, I go out and pick them up.
And on georgian or leaded work, WFP is far superior, regardless of whether or not the trad window cleaner uses a cut down squeegee or a buffing technique, there will be far more mistakes made on the glass, either with lines from detailing or kicks and squeegee lines, or with smears from buffing...especially if the sun is at the right angle, THEY WILL show up.
Of course on badly oxidised windows, it is far harder to get a spotless finish with WFP, and in those circumstances there are times when the only option to get a really good finish is to use trad, especially on georgian work, but that isn't to say you can't get the work to a readily acceptable standard.
So do I trust WFP?
Well, yes, mostly I do, I'm experienced enough to know when I'm going to have a problem, and usually I'm also skilful enough in most circumstances to do the job to a high standard. When WFP can't hack it I will use my trad gear....but NOT on upstairs work (well, very rarely anyway :
)
Ian