Because of bad structure, bad things could happen, even if it appears that, on the surface, things are going well. Poor structure could destroy the work that you put into keyword level tracking URLs, device specific bidding, and granular site extensions.
David Rodnitzky wrote a column for Search Engine Land entitled ‘Why Account Structure Matters For Every AdWords Account.’ In the column, David describes a scenario that he found himself that matches this problem when dealing with a client’s AdWords account. He goes on to talk about the solution to how you can fix this sort of problem if you are ever privy to this sort of account in your SEO lifetime. I’m sure that won’t be too hard of a thing to run across.
To read David’s column, check out the link below:
http://searchengineland.com/why-account-structure-matters-for-every-adwords-account-174214