What you’re mentioning sounds more like a case where the company was not a big success and things like heavy dilution came into play? In that case, I’d hardly call it “getting screwed”, that’s just a risk of doing business with a startup that failed to execute properly, or lost against opposing market forces.

In other words, when the company goes bad and it’s forced to take heavy dilution or aggressive liquidation preferences it’s obvious that common holders are going to get wiped out. But, and that’s the part interesting to me, what greedy behavior from a company can make the common holders get screwed even when the company sale is a big success?

An example of getting screwed was the clawback clause that the Skype employees had, which gave the company the right of buying back the exercised shares from common holders at the original exercise price rather than the market value at sale time (or something like that). That’s called “being screwed”, not seeing your shares getting wiped out because your founders had to dilute the common holders (which many times includes themselves) 50% during a difficult fundraise.