I almost always pull comps before I go out to inspect. Why go twice? Even with high end properties I can reduce the number to look at to a dozen or so, worst case. Then sort out which are best after.
Tax records and sometimes MLS gives some info, usually. I always look to see what I have before I call. Whether it has good info or not, I always ask when setting the appt if the house is x,zzz SF, do you have a view, any room additions, remodeling? That way by the time i go out there, I hopefully have a decent idea what I'm going to see.
IMO, asking them to describe it in detail is asking for a long boring story, or a blank silence, in some cases at least. If it works for you, more power, but I have'nt had much luck, although homeowners may vary.