I just seen this quote from Andy Murray after his latest match...
.."I didn't hit it unbelievable today but I worked hard," Murray told Sky Sports.
Appalling, in my humble opinion, but perhaps it don't really matter.
I think what grates with me is that it would be no more difficult to say it properly, and from what I remember of hearing him speak, he normally gets it right. If you've been brought up to know nothing better, it's more forgiveable. Although sometimes reverting to poor grammar is a deliberate act for emphasis.
Normally I am a bit judgmental about poor grammar*. However I saw a clip the other day from a Buckingham Palace reception for Olympic athletes. One chap said to the Queen "We loved that Bond thing you done". and for some reason I loved that - the fact that someone felt able to be entirely natural like that, talking to the Queen, By and large, I think I'd rather people spoke the way they grew up, than put on artificial airs, which often leads to other errors anyway.
*Other things too. I have a workmate who holds his fork like a shovel, fist round the handle. He's a nice middle class chap from Oxfordshire, and a graduate musician who played for exams and choirs when he's not working with us. It grates a little for me every time I see him holding a fork, although I've learned not to be bothered. I guess I'm more judgmental about people I already dislike anyway...