Tom, the brain is a wonderful thing - when you create this affect on your own photos, your minds eye recalls and sees the original first, ignoring the tilt-shift effect.
Your mind is fixing it..
But when you see one that someone else has done, then you see their result first because you have no recollection of the original.
It's weird, but that's exactly what I find. But, go back to your image a month or so later and it looks better first up (until you recall the original again )