What Makes a Data Set Good or Usable?

When i first get a data set, i'd like to look at the data to literally go column by column, or row by row. It's not the approach that most peopleh take with data. I really want to know the data before i treat it like a scientist. And if i can't put my finger on anything that makes it unique, then i know i'm not going o have a good outcome. Give me an example of a day to set that had something that you've never seen before.