VCs are making financial risk decisions based on many factors, and they aren't obligated to research before they buy any more than I am obligated to research stocks. Not only that, but they are certainly aware that most of their investments won't pan out - they just want to make sure they've invested when the next facebook comes along.

Therefore, I think startups should put little weight on how much investment was given to them (or others) - it's not the same as "validation" that the product is going to be useful. That comes from actual customers buying the product.