:bsmilie: I love option 2... Ha ha!!
My worst problem with glasses is that they steam up or get in the way with straps, bracket, etc flying around.
From my POV: Assuming the shutter speed is adequate to avoid camera shake, and the pictures are taken in both situations with on a tripod or solid surface and timer:
1. Glasses related:
High astigmatic prescriptions can give incorrect images depending on what portion of the glasses you are looking through, head tilt can exaggerate this i.e. it might look like the sharpest image but in actuality it isn't.
Myopic (short sight) glasses minify images anyway and this is worsened with using cameras as there is also more space between the eyepiece and eye, compared with no glasses. The apparent depth of focus is greater, leading you to believe that the image is still focused when it is off a bit.
Assuming your glasses do not need updating, in general dioptre adjustment is only needed for hypermetropia (long sight) or presbyopia (age-related accomodative loss) people so that they can read the viewfinder data.
2. Camera or Lens focusing error.
I had a camera which was back focusing which caused something similar (drove me crazy until I did some testing). All things being equal, I think this may be your problem.
Good luck!