plenty effort with little/no reward? Why not ask seller to go to local bike shop and have someone there check it out? (If a seller doesn't want to take it in to a dealer then that may be your first warning sign). I understand there may be a LBS which doesn't want to help or doesn't have the time, but I often have those requests where people bring parts or bikes to me to check first. Sometimes frustrating, sometimes I can rather recommend new sale which benefits shop and customer- scenarios vary considerably. Used purchases are always a risk. The buyer knows this, but the price is the deciding factor. if it too good to be true then it usually is. If sales contacts are what we need then perhaps a database can be created of people willing to help in the case of validating product and authenticity.