How to buy under-market-value properties

For me to know that I'm actually buying good value real estate, I've researched my areas, I've gone there, I've spent time on the ground, I have no emotion to the property at all. I look for a whole bunch of suitable properties that I would look at purchasing and, say there was ten, I would just put low offers on the whole ten of them. So the best way for me to buy under value is by really low balling, insultingly low offers and you wait for the real estate agent to come back and say "Look, the vendor won't take your offer but let's negotiate". That way you know that you're going to be buying well below market because they're a desperate vendor who needs to liquidate and get out.