Something like this?
Lens cleaning
The best two ways for lens cleaning is to use a lens pen or small bursts of compressed air. Do not blow, it will condense. Use a small pump.
There are other ways on the web, but do not trust those. In fact some of the methods can or will destroy the lens.
If the lens is scratched, then try to ask the seller for a replacement. The scratch can't be repaired. If you can't get a replacement from the seller or elsewhere, you can get a decent replacement inside a old camera or similar if you're lucky. But that would be the last option.
And lastly, don't think about if the lens is clean or not, because you might be fooling yourself and clean it in vain. The less you mess with it, the better the lens, it's that simple.
