Tell me about valuable oil paintings...

Just looking for personal experience, anecdotes, stories of forgeries, finds, scams, surprises, insights, whatever. Here are some general questions I have:

  1. Do you own any valuable oil paintings? (if so, did you buy, inherit, find, etc.). Are you a collector/hobbyist/enthusiast or lucky SOB?

  2. What artists or genre/school/style of paintings do you have?

  3. How do you know how much it is (they are) worth? What is the assessment process like? Is there a website (aside from ebay) where people share photos of painting they are trying to sell? Is the internet a good guide for figuring out approximate valuation (assuming the artist is listed on auction history sites)?

  4. If you search for paintings at yard sales or antique shops is it likely you will stumble across a valuable painting that is dirt cheap?