My parent's have an ex racer .
He was 4 years old when they got him and had been incredibly successful. So much so that even though he's only 5 he looks older than my 14 year old lab 
When they first got him we were eager to get him used to our family dogs (we are very close and the dogs are an extension of the humans so come everywhere with us)
We assumed he would be good with other dogs.
Nope
He wanted to dominate and be in charge. He didn't like quick movements and he came to blows with my brother's collie. Collie is a grumpy arse and we no longer meet with dogs in tow.
However he also had a set-to with my elderly lab. She blindsided him while chasing a ball and he grabbed her by the neck and pinned her to the ground. I thought he was killing her.
Turned out she didn't have a single mark, he was warning her. She wasn't phased and after a few weeks we tentatively reintroduced them and she went back to him, he greeted hear excitedly and they sniffed and a year on have since become firm friends. There's no way this would happen with the Collie because his personality is totally different to my lab, so we wouldn't risk a second introduction.
Dad got a yellow warning lead and used a muzzle while they worked out how he reacted to dogs. They discovered he adores humans, especially men. He really likes tall dogs - especially other greyhounds (he goes to a dog sitter who has 2 ex racers) but is very wary of little dogs . He quite likes labs and I think this is because of my dog.
With the family, the youngest at the time was my son and he has grown-up around ex racers (step mum fosters) so he knew to leave him alone. They interact lovely, my son is very calm.
He doesn't guard his food, will eat happily in front of my lab.
He will not be told where trying to steal food is concerned. He is a nightmare. He goes in his cage when we eat (his safe space)
We found a video of him on YouTube, winning a race. None of us thought he would react but he was up at the Tele and very excited to hear the sounds of his previous life.
He stands watching birds and aeroplanes for ages.
He doesn't like next doors cat.
He has several big teddies, 2 dog beds (and the sofa) in the living room, his cage in the kitchen, 2 single beds upstairs and every morning he gets in bed with mum and holds her hand with his paw.
He's not very cuddly but will come to us when he needs reassuring.
His farts are noxious and often.
He has a terminal kidney problem which insurance covers, so he's not going to live to an old age but he will live like a king.
Sorry long post, but I could chat about him for hours (and as my username states, he isn't even my dog!) 