there will be alot of houses that go back up for sale next year around here-the market has tanked and alot of folks that already bought elsewhere are cutting their losses by converting to rentals to cover their costs (after the houses have sat for months).
there can be loads of reasons something has'nt sold-competition, house needed updating/general declutter-cleanup, maybe it was overpriced back then (and sometimes drasticly underpriced scares away buyers too-they assume its because there's a hidden defect or psycho neighbors!).
i think if i were doing a purchase of a fsbo i'de contact a reputable agent i trusted and cut a flat dollar amount to represent me (they will have an easy sale, no out of pocket expenses so they may jump at the opportunity). agents talk to one another and may be able to find out/may know if there was anything odd about the last time it was for sale. you also get the benefit of having a 3rd party that is knowledgable about real estate laws, trends and the like (and they tend to have great connections to get building and pest inspections, appraisals and the like done much quicker than a private party).
i know real estate attnys. are standard in some states (not here)-but unless an attny. is absolutly needed, the expense and lack of access (they tend to be less available and less able to go out to the property with you to address questions/concerns) makes me less likely to consider using one.