Fair?

I saw this in Baltimore last Sunday. The question is: Is guerilla marketing ethical? No question that Boost mobile may have to pay a fine for there work here but is it fair to graffiti artists that try to express themselves to in their work while some companies do work like this to sell themselves as "urban" and "cool?" Ji Lee uses graffiti work to point out the contradiction of personal vs. corporate work, not to sell it and he works for fucking google! No doubt I would love to work with Ji, we are completly on the same book.