Banksy

"The people who run our cities dont understand graffiti because they think nothing has the right to exist unless it makes a profit. The people who truly deface our neighborhoods are the companies that scrawl giant slogans across buildings and buses trying to make us feel inadequate unless we buy their stuff.

You owe the companies nothing. You especially don't owe them any courtesy. They have re-arranged the world to put themselves in front of you. They never asked for your permission, don't even start asking for theirs.

Any advertisement in public space that gives you no choice whether you see it or not is yours, it belongs to you, its yours to take, rearrange and re use. Asking for permission is like asking to keep a rock someone just threw at your head."