Pros and cons of wiping a new Mac? Coming from the PC world, most made-to-order manufacturers (e.g., Dell, HP, Acer, etc.) all have annoying little addons which I consider spyware/bloatware--things like toolbars with ads. When buying such PC laptops, I would always reformat their hard drives and then install just Windows (and drivers), ensuring a blank slate without any bloat.

I don't believe Apple includes such spyware/bloatware. Nevertheless, when purchasing a new machine direct from Apple, are there are any advantages or disadvantages to wiping the existing drive and performing a fresh install of OS X?
There isn't any advantage to wiping and reinstalling OS X on a new Mac direct from Apple.  You'll end up with the exact same drive contents.  I can't think of any difference between an Apple-imaged Mac and a self-imaged Mac.