I don't know about anyone else, but when I don't see any interior photos, my first thought is: "Uh oh, I wonder what's wrong with the inside. Similarly, when I don't see exterior shots my radar goes up as well.
Now, it could be that the day the listing agent went by to take photos, the house was locked up and s/he couldn't gain access. Of course I see that as a b.s. excuse, since s/he could have arranged with the seller to go back another time to take the photos.
To me, personally, an agent does a tremendous disservice to their client when they either don't take photos or take lousy ones. I guess lousy is better than none but still....The vast majority of home buyers these days search for their future property on the internet. If they are like me, I won't even look further at a property unless I see photos.
I've got to say, Fairviewcottage, that in my experience it is rare for a professional Realtor to post a listing without interior photos - but I have seen some. All I can say is "let the buyer beware!"