Almost everything is negotiable when it comes to my thinking a photo is a good one.
The one exception is that when viewing the photo as a contact print at a normal reading distance, or when viewing it as, say, an 8×10 print from 12 feet away, or any equivalent combination of size and distance I must either (a) be able to see what it is a picture of or (b) be interested enough to make me want to take a closer look.
Meeting one or the other of these criteria does not necessarily mean I will think the photo is a good one. Meeting neither of them does mean I probably won’t bother looking at it more closely.
Of course beauty is in the eye of the beholder. What attracts my attention in a glance across the room will be of no interest to some others. The Foggy Morning picture I posted a while ago would not interest me at all in a contact print or distant print on the wall were it not for the two uprights with no obvious foliage. I find most landscapes with nothing large in the foreground boring, unless something man-made breaks up the natural forms.
Are there things about a photo that would make you lose interest in it at a first glance?