Is Spam Really a Big Problem?

Here is an article on netimperative about some interesting research sponsored by moneysupermarket.com. The key take aways for me are:

• The average consumer only receives just over 10 spam messages per day - for some reason this seems low.
• 90% of consumers do not take active steps to stop spam. I cannot decide if this is good for legitimate marketers or not. On the one hand this increases clutter in the inbox but this also means that we do not have to worry about our opted-in readers accidentally creating false positives. I would be interested to hear your thoughs on this.
• Spam still works - 14% of respondents admitted to having clicked on a spam.

One of my concerns however is how they defined spam. As we all know there is the legal definition and the consumer's definition. Consumers think any message that is not relevant is spam. So this begs the question, "how many of the 10 spam messages per day are legitimate emails that the respondents opted-in to receive?"