My 12.5" primary Has a layer of dust too. I'm not keen on the idea of cleaning it. I did that with my 4.5"....It had a pretty good coat of crap, so I noted the view I was getting, took it out & cleaned it, then compared the views. No appreciative difference at all to my eye. But it's very hard to ignore the fact that it's got dust on it....It wants you to take it out & clean it straight away! I say resist the urge Astroman IMHO
