Alright. Here's my confession to all of you of my obsessive behavior....in regards to my photography. For those of you unfamiliar with my creative past, I worked as a production artist ON digital photos for a good while before taking up the photography trade/hobby/passion myself.
So it is perhaps because of the 100's of hours I have spent looking at photos full-zoom 100%/200%/300%+ on my screen that I am completely obsessive about the sharpness of the intended focal point of my photos.
Allow me to demonstrate what I mean:

The intended focal point, the eyes, are in sharp focus. (100% crop)

Not so much here... (100% crop)
Okay, so you can see why I would want a photo to be focused as intended, but once you stop looking at the images at a 100% pixel level and start to view them as a whole, does it
really, really matter that much? Probably not.
Let's take another look, this time at the images as a whole:

Eyes in Focus- Whole Image

Eyes Out of Focus- Whole Image
(Ok, so he was looking a little dorkier in this picture, too)
I have deleted so many decent photos because they didn't meet my standards for sharpness. Because if I printed this image at 20x16", it would be apparent. But in truth, I don't ever print that large, and many more of my photos will only be viewed at MUCH smaller size and resolution on the web.
Am I going to stop being anal about this? Not likely...
No one have ever accused me of being a perfectionist, but even if no one else will ever know that an image didn't meet my standards, I will.