At the best places, I assume this happens a bit, but it's pretty easy to ignore it completely and still do well by being a good employee.
At the worst places, it's apparent even to someone unaware that something is up, because people will make comments that are totally nonsensical unless you're neck-deep in the politicking. It also shows when smart people make obviously awful decisions - they're probably getting something out of it other than the good of the company.