It is certainly possible to do close to perfect. Here are my scores:
Academic 28
Perceptual 20
Quantitative 25
Reading 29
Biology 26
Chemistry 29
Organic 29
Total Science 29
I don't think I missed any questions in chem, ochem, and reading, which leads me to believe the highest score you can actually get is a 29, not a 30. That being said, I think it is possible to get a 29 in chem and ochem if you really want it. The chem topics are quite straightforward and if you learn them all...it's possible. Ochem as well, since it is rather basic topics and everything is multiple choice which makes it easier.
Biology just has too much information to really be able to prepare for a perfect score, but I'm sure it's been done by someone on a lucky day. Reading I got lucky, but you can prepare to get at least mid 20s. Math should be possible if you really go crazy with it, but it is very fast and a little tricky here and there. There is no way to score perfect on the PAT in my opinion, the angles alone will put you out of the running.
That being said, I wouldn't go crazy with the DAT. I studied about 3 weeks 2hrs a day and then a month 5 hrs a day. I wouldn't put tons of time into the test just to get a crazy score. It doesn't hurt, but I don't think it helps me any more than a 22 or 24 would have.