I forgot to refrigerate milk that I bought at the store; how do I know if it has gone bad?

Ideally, milk should be stored around 40F. For every 18F increase in temperature, above 40F, the spoilage rate of milk doubles. Harmful bacteria start to grow rapidly when the temperature of the milk exceeds 45F. Here's a link with more helpful tips!

*Megan Watson, 2010-2013*