That being said, the BP oil spew can teach us of the primary lesson that Karl Marx taught which still holds true - labor has been and will always be exploited to some degree under capitalism.
Now, we can differ in opinion on exactly how/what is being exploited by the capitalist (business) on the laborer (the average Joe), but this exploitation can explain why some people are expressing reservation about talking down or financially hurting BP, despite their obvious failures. The reasons often provided often come down to just one thing: 'Americans work for BP, we are dependent upon them and other oil companies to live.' I like to imagine that Marx might be able to translate were he alive:
Capital is dead labor, which, vampire-like, lives only by sucking living labor, and lives the more, the more labor it sucks.-Karl Marx, "Das Kapital", 1867