Had the same with a club mate. £30 JJB offer on a 505 GM Hero brand new. Show the bat to a team mate and he says, "I'll have a net with it and if that goes ok, use it in a game and I'l let you know after that". I wasn't impressed with his suggestion of making it worth less than it was already.
Even worse than that, the guy you will see with me on the AOC gear test, I got him a blank CA 10000 last season (He's a student).
Played like a plank for 2 weeks, I couldn't understand why. Then I was stood around explaining to the youngsters that knocking in makes a huge difference to performance and longevity of the bat, when he turns to me and says "do you think I should knock it in then?".
At which point, I snatched the bat off him and, took it away myself to knock in for a few hours. He went on to score over 1500 runs with it after that, including some monster 6s in a top score of 161*.
Still tells people I sold him a dodgy bat! I can't write here what I said...