Problems cleaning windows -driving me insane

[unlucky67]

Just been cleaning my windows - I hate doing it and it seems to be one of those jobs that is more of a pain than it needs to be....
They are double glazed units approx 15 years old...I clean them with soapy water, optional vinegar and a squeegee...but they were the same when I was given some windolene to use up ...
Firstly does anyone else get black gunk from the seals around the units? - it isn't not mould and it doesn't seem to be grime - it is almost as if it is something coming out of the seals. They are the same inside and out and have always been like this (10yrs)...never had double glazed windows before I lived here -Is it might be a common thing- are all double glazed windows like that? just means I have to keep changing the water and I get more streaks...
Secondly I think in the past someone put some of that 'never have to clean your windows again' spray stuff on them - I can see it on the surface when wet but not when dry ...means I can't tell if they are clean properly until I dry them off -when if it is dirt I have to do them again...
They could do with replacing anyway (warped frames gaps between units and frames) just keep thinking they'll do another a year...except when I clean them and I feel like ripping them out ....

I would have a go at them with an e cloth, there's one especially for glass and it is fab. They take a bit of elbow grease but they do get that film off.
Although you probably won't take my advice as I see you've just done them, so me telling you to do them again with more effort and money spent may not seem appealing!

I will admit to only doing them a couple of times a year - I use e-cloths for other stuff and agree they are great - in fact I have one for glass I use for mirrors/shower screen etc but the black gunk is almost impossible to wash out so I tend to use rags (old terry nappies...)
Do you get the black gunk from the seal as well or is it just mine?

No I don't get that, is the seal kind of disintegrated? Maybe someone has put something on the seals that is making them break down. I had unfortunately worked in a double glazing company and never heard of this before.
Sorry not to be more help :)

Hi, i fill a bowl of warm water with a tiny drop of wasing up liquid and a couple of caps of white vinegar, i clean windows with an old vest or rags and then dry off with newspapers - and they come up really really good!