I purchased a Nikon 105 D micro lens from a Nikonian and upon close examination it has large specs of what looks like dirt. The specs are red in color and much larger than the typical dust specs already in the lens. They are also under the first element. I've emailed the seller about the dirt in the lens but didn't ask for a refund yet. If the specs won't harm the lens I may keep it. What would you do? Paid $333 which included shipping and a Nikon polarizer. Ohterwise the lens is very nice cosmetically and fully functional in limited testing.
The first question I would ask (myself) would be, "How was the lens advertised?" and go from there.
I guess by "fully functional" you mean functioning mechanically - that auto focus and VR work, the diaphragm opens and closes properly, manual focus is smooth, and the 3 switches function - without regard to IQ?
I don't think it's rust since the specs are a few mm's from the edge. They don't seem to have an effect on image quality, it just looks like big dust specs. Otherwise the lens is very nice. I just got an email from the seller and have to opportunity to return it but want to give it a try before making a decision.
Dust is usually a matter of only minor concern IMO. The thing is, all lenses contain dust - every single one of them - even lenses fresh from the factory. Minor dust does not usually affect image quality in any way, as you've noted with the lens you're testing.
I send my most often used lenses to Nikon every couple of years for cleaning, lubrication and adjustment, something Nikon refers to as CLA. If a couple of your own lenses are due for some CLA TLC, include the 105 in the bunch and freshen it up. It's likely that the 105 has never had a CLA anyway, so it's likely long past due.
I think relatively spotless 105 D lenses are getting hard to find because they generally get a lot of use because they're terrific lenses.