Now turn the lens around and look in through the back.
Most lens problems are most easily see when looking backwards this way.
Often a lense of this size will have between 4 and 7 elements and be in 4 or so groups of lenses.
Because these groups are in separate locations inside the lens , some more forward and some rearward , you have to be careful to focus your eye on each surface in the lens.
It sounds easy to say this , but when you try it , you will soon go cross eyed trying to focus on something almost invisible.
In fact , the more faults a lense has the easier it is to focus your eye on the fault.
A real clean lens is a challenge.
Inside the lens you may find black specks or stuff ??
It is likely these specks are lens adhesive or black paint that has flaked off and fallen onto the element.
The older a lens gets ... generally , the more black specks it will have.
Black specks are not a very bad thing to have inside the lens.
As they are black they will not cause any flares or reflections.
These can be removed with disassembly and cleaning , but they would have to be very numerous to be bothered with.
Seen clearly on the picture below is a big black speck and more surprisingly a scratch.
This scratch is quite unusual , because it is not on the front element or the rear element , it is on a interior surface.
This means that it has been there since manufacture :-O
Unfortunately , this is not so uncommon on Kiev lenses.
Even though this scratch shows up clearly on this picture , I have looked a number of times later and it is almost invisible.
I would not expect any noticeable effect on pictures with these faults.
Moving the lense around again to get different off axis light entering it can help you spot more objects inside the lense.
Here are numerous dust particles up near the front element.
