I grew up in a household that had a total of 13 dogs. As an adult, I interact with between 70 to 100 dogs every work day (not counting the ones I live with, and the less said about them, the better). In short, I have had a lot of opportunity to experience canine behavior.
When a new tree is planted in area common to lots of dogs, it's a very big event. Many dogs will try to "make their mark" on the tree by pissing on it. The more thoroughly they urinate, the stronger a message they feel they are sending to all the other dogs who will inspect the tree and the collected "smell comments" on it.
Spend a lot of time with dogs, who like us are strongly social, hierarchical, and pack-driven, and you will see how similar people's behavior is, once you scratch off the veneer of our intelligence. For example, in the comic book world the latest Big Tree is, of course, Countdown to Infinite Crisis. It is, in fact, the central tree in DC's new grove, soon to become a forest. It's the most important tree planted since Crisis on Infinite Earths.
So, naturally, every good comic-reading dog has decided that, in order to make their mark and show off for all the other dogs, they have to piss on it. And the stench streaming from their little weblogs is fierce! Yet every time Jeph Loeb's pukes up onto the sidewalk some half-digested pieces of the worst of the Silver Age that he found rotting in the sun, these same dogs run over to roll in it gleefully, hoping some of its stinky aura will adhere to them.
Dog have great astuteness; if they bark, pay attention. But do not take their advice on comic books. As a human being, feel free to look up and admire the majesty of the tree, its powerful roots, its far-reaching branches, its striving to great heights. Don't waste your time sniffing the droppings of those whose world includes only those things right under their noses.