I grew up in a college town, and live close to an urban university now. I haven't marketed to students (yet), but one thing that I have seen in both places is an explosion of new townhome/condos, all pretty high-end with all the bells and whistles. This appears to be siphoning off all the more affluent students (or students with affluent parents, I should say.) Also, there are also a lot of new apartment complexes geared towards students (free wi-fi, shuttle transportation to campus, etc).
This seems to be pushing the SFRs in two directions: high-end and low-end, with not much in the middle. Because of the new properties on the market, SFR rents seem to be somewhat stagnant. There are certainly a lot of decrepit properties of the kind you describe; on the other hand, a recent fire in which two students died has put a spotlight on these practices.
What I see in my hometown is what appears to be major overbuilding. It's a big state college, and they're not building any more on-campus housing, but the amount of student-oriented apartments/etc being built is unreal - it's as if the last five years never happened. Personally, given that I feel that universities are going to go through some major challenges in the next decade (facing online competition, MOOCs, student-debt challenges, etc.) I'm hesitant to get into any student-oriented housing that wouldn't be strictly short-term.
With that being said, if you're looking for quiet student tenants - market to grad students. They still will do dumb things, but generally they're past the wild party stage, they're more responsible, and appreciate quiet. I can speak from experience, though, that their income is low, so you'd have to have an appropriate property.