I had both my pups cropped at about 8 weeks old. There was no blood or mess. They were romping and playing around as soon as I brought them home from the vet. Their ears were all taped up, with a styrofoam cup in the middle. : ) As I recall they had some pain meds for a couple of days. There were stitches, of course, and it got a little scabby where the stitches were. The vet said to combat itchiness (not pain, itching) to rub a little neosporin on there, which also got some of the scabbiness off.
Then they went back to the vet, I can't remember if it was one week or two. In one case, the pup's ears were standing just fine already. The other puppy had to have her ears taped up again, maybe even a couple more times, because they weren't quite standing. For a long while she had one ear that kind of flopped, but lo and behold as she got older it started standing up just fine.
Anyway, I'm a real animal advocate and really questioned whether I should do the ear cropping or not. But they didn't appear to be "suffering" much at all during the process and I'm really glad I did it. Like I said, though, they were only 8 weeks old when I had it done. I think 12 weeks is the absolute cut-off, at least with my vet. The vet also mentioned that I cared for them really well after the surgery and really followed his instructions well. He said some people don't and the ears can get infected, etc.
My vet doesn't do ear croppings anymore, by the way. He was so good at it people would come up here from Seattle (I'm in Anchorage, Alaska) to have him do their show dogs. But the clinic he works at decided it was inhumane and they didn't want to be associated with it anymore. So he just quit doing it. But dig this, the clinic DOES declaw cats! And that IS inhumane. What a bunch of hypocrites.