Sorry, but there's no one-size-fits-all answer regarding what is acceptable and unacceptable. You should be taking into consideration the intent of the site to help determine what is acceptable. Let me give you an example:
One of our landing pages had a bounce rate of 58%. This was problematic because the landing was designed to generate leads. In essence we only had a shot at converting the 42% of traffic that didn't bounce when they hit the page. And of those, we were converting about 6%. For that particular product, we converted 5 out of every 100 leads generated, and the average lifetime value of the client was about $3K.
Long story short, it worth our time to deal with the higher bounce rate because the potential value of each lead was rather substantial. So, take it on a case-by-case basis, but remember that it's been said Google takes bounces rates into consideration as a ranking factor.
