I have recently purchased a Leitz M Super Angulon 21mm f3.4. In mint condition externally that is.
I have noticed that the lens was fogged up in front and in the back, because of this I have asked shop owner to send it for cleaning.
It came back, and I have checked again and noticed that some part has been cleaned perfectly, but some parts were left unlearned.
Most noticeable part is in the front element, around the edges of the lens. (It might be on the first element or on the second
element reflected to the first)
I have also, sent my Summaron f2.8 for the cleaning as well and it also, came back with some unclean spots.

My questions here are, First, will fogging in the lens affect the quality of the picture?
Second, is it possible to clean the old leitz lenses perfectly, since if you are to do this I would think one must disassemble
the whole lens and rebuilt it again? Can anyone perform such task?
The owner of the camera shop told me I will be taking a lot of risk doing such, thus it may cause the misalignments
in the lens structure and quality of the picture may be affected by this. Because of this He told me to leave it as is for now.

Is anyone can give me a good advice on this issue so that I can sleep well?
PS: I have Sumilux 50mm and Summicron 50mm, as well. They got foggy as well so I sent them for cleaning in a past.
They came back with no such problem. Is it true that wider angle lens are more difficult to clean, than the
50mm or 90mm lenses with less number of lens elements?