The results you posted show clearly some limitations of photogrammetry. But with these type of objects I would guess even structured-light scanners would struggle (depending on the accuracy requirements and preparation work).
Two things that immediatly come to mind is the uniform surface color of the glasses frame and the shininess of the surface. Both individually are bad, combined even worse and I don't think you will be able to achieve any kind of good results.
My suggestion would be to coat the frame with some diffus reflecting substance (spray paint, for instance) and additionally trying to get some texture onto it (splashing some acrylic paint or similar).
For thin objects there has to be a fairly high amount of overlapping images, since the surface changes rapidly when only change the rotation slightly (especially in vertical direction). It is a good idea to have a well textured background as long as it stays in the same position relative to the glasses.
Also try optimizing the image-framing of the glasses, they should be covered by as many pixels as possible.
Good luck! Quite a challenging subject you have there.