Danny's look when Mac said "I'm with her..." was priceless. For one brief shot, Mac obviously had a hard time keeping a straight face - either that or Gary Sinese did. It was small, so who knows whether it was in character or not!
There were several breaches of normal practices. Most notably, Danny wore gloves to retrieve the bullet from the bloody water but then handled it with bare hands afterwards. Ironic that at that point in the show, I thought of AIDS. Then, of course, there was Mac handling the credit card.
I can forgive the breaches of etiquette with Stella more, because they are more in keeping with the panic that someone would really have if they'd cut themselves with bloody glass. I think that if that happened, your first thought would be to wash immediately, no matter whether you were at a crime scene or not. And, I'm not sure this really falls under the same category as people mentioned with Greg at the crime scene in Las Vegas -- is it possible that given the circumstances, that they didn't regard the entire apartment as a crime scene? As for the contaminated piece of evidence, I imagine that she just didn't turn that piece over to be tested. It isn't necessary in all crime scenes to test every single piece of something -- we've seen cases both ways. I'm not excusing it as right, but quite possibly realistic for someone in that scenario. I also think the reasons for Stella doing what she did and Greg's carelessness are so totally different that a supervisor would handle them in different ways -- not to mention that Mac and Grissom are two very different types of personalities.
I can understand why she didn't tell anyone and went to the hospital on her own. Some people -- even ones who are very supportive of their friends -- have a hard time sharing their own problems and asking for help and support when something happens to them. And the worse something is, the harder it is for them to let people in. The horror at the possibility of being exposed to AIDS being realized when Sid told her that the victim did indeed have AIDS would have been so overwhelming that it might feel impossible to breach with friends, especially if she were worried about being faced with pity rather than support.
I thought both cases were good, but the ending of the first case in particular was a little too much of a stretch. The woman didn't know she'd been shot -- ok, maaaaaaybe, but surely she'd have bled on something other than what she showered away. Pillow or not, you'd have to be a pretty sound sleeper not to hear the shots that close, too. And for someone else to realize that she'd been shot in the head when she didn't know it herself, a little too much of a stretch of the imagination. The other case I could buy more, but how would Mac have known about the syndrome she had where she didn't recognize her own reflection?