I agree that underhanded tactics to get work is wrong.
Deliberately finding out what someone else charges and quoting a cheaper price to get the job is not good business.
However, if you are out canvassing and someone says ""OK can you give me a price", Its a job that will take maybe 30 mins and you say £15. (In London)
THEN the housholder makes you aware that they actually do have a window cleaner and he charges £18 what would you do?
I would say to the housholder, "Are you happy with the work he does?" If they say yes then I'd likely leave it for the sake of peace. Though I'd be tempted to take it.
BUT if they said £20-£25 i'd think, well someone has been making GOOD money from this job, and if you price that high, its good while it lasts but that's the risk you take.
There's nothing wrong with charging the going rate. If someone comes along at the going rate, fair enough.
Even £15 is good money for a half hour job, lets face it.
Would you say that is the same as undercutting? I don't think so.
Then there is supply and demand,
At one time window cleaners were like gold dust. Now there are more and more window cleaners coming on the scene. Hence more supply. More supply, less demand.
You might get away charging extortionate prices to people who were at one time desperate for a window cleaner, but when others come on the scene, you run the risk of losing the job.
Be fair from the outset.