Its not hard at all when you look for the parts that give it away.
The only one that might be tricky is the golfball but thats just because the grass has been worked with in a graffics program. Look for the little damages on the golf ball, they would never be in a CG.
Everyone of the CGs are completely obvious. I didnt even need to enlarge them except the nails
Photos always have something that you wouldnt necessarily put there in a CG. CG's always have tones that arent realistic (the grass for example)
My first graphics teacher told me I would never trust photos again now that I was learning photoshop. What a load of crap
it's only a matter of time before CG gets advanced enough to decieve even the most experienced of spotters.it's still a developing technology so while photography is still a reliable source is most cases i reckon we haven't seen the best of CG work yet.
in any case that quiz didn't exactly comprise of superb quality pictures,which might explain why everyone did so well.