Just had double glazing and can't seem to get the windows as clean as I would like. Seems to be several layers of greasy substance on them. Tried all usual things. Any advice welcome.
hot water with a tiny dash of washing up liquid and a splash of white vinegar applied with a bit of old towel to really give them a good 'scrub' polished off with newspaper (B&W and preferably a few days old)
Try Cif and a green pot scourer, then rinse off while wiping with a wet cloth. It works on car windscreens when they get greasy during hot days in summer.
When I drove coaches we would use the same method as rattygirl says to get mens hair grease off the windows because they would lean their heads against them when sleeping, and the windows would gleam, and I would use the Financial Times as it is a good quality paper.