My Rocky bloated/twisted 4 months ago. His symtoms:
Restless, he could not get comfortable. He would repeatedly lie down than get up. He tried to throw up but nothing would come out and he was wimpering. He was able to get into the van to take to the emergency vet where he was x-rayed. His stomach had twisted and he was put down 1 month before his 12th birthday. The signs were pretty clear, when he could not sit still, wimpering and trying to throw up but nothing comming out. He was very uncomfortable.

I do not think Bloat is that common. Rocky was a very deep chested dog, a worry wart and he was almost 12. Maybe these contributed to bloat. His sire also died of bloat at age 9.
When I got my first Akita that was the 1st time I ever heard of bloat. I worried sick about it and Sheba never got Bloat. By the time I got Rocky, I learned not to worry about it, but be aware of the symtoms just incase.

A dog who has bloat will be very uncomfortable, stomach might be extended and the signs will be clear if it is happening.