I remember watching a documentary on the Chuvalo/Ali fight, where Chuvalo talked about Marciano being brought in as a "mentor figure" for Chuvalo, and Rocky exploiting him and taking a bunch of money from him.

And just recently I borrowed Bret Hart's book from a friend to read on a roadtrip. There is a story about Bret's father, Stu, flying Marciano in as a "special guest referee" for one of his wrestling events and Rocky intentionally screwing him over. From the book...

"I'd learn years later that Marciano was a horrible cheapskate; when he'd left town he intentionally misled Stu into writing him two cheques, each for the whole fee. Even knowing how badly my dad needed the money, he cashed them both. Despite my dads attempts to get him to send the money back, he never did. About a year later, Marciano died in a plane crash. My mom didn't shed any tears."

Its kind of disappointing hearing one of the sports all-time greats and supposedly most classy champs of all time acting like this outside of the ring.