How much do these spammers like to do business?

The more email addresses you have, the more spam you will receive, unless your name is John C Dvorak of course.
I sometimes take the time to respond, if I am really bored. Here’s one of those cases:

>>Good morning,
>>
>>I apologize for this disruption and hope you do not mind me
>>dropping you an email just to see if you might be interested having
>>some search engine-ranking work done on your site. We specialize
>>in web design and search engine optimization that ranks our clients
>>in the top five on Google, Yahoo, MSN and many others, for their
>>specific search terms. Our services are tailored to
>>companies/firms such as yours that have the potential for a large
>>volume of web-generated business. Recently we ranked one of our
>>clients #1 in 55 categories and in the top 5 in 145 categories.
>>Their business is booming. I would be happy to send you
>>information that is more detailed and references if you wish.
>>
>>Best wishes,
>>
>>Brianna Foss
>>“Not All SEO Companies Are Created Equally”
>>858.274.5275

My response was as follows:

>I just had a question:
>
>Is this actually a good idea? I heard that bmw.de was banned from
>google for doing stuff like this.
>
>I await your reply.
>
>Kind Regards,
>
>Nick
>Webmaster xxxxx.xx

Their reply:

Nick,

I definatly would not recomend you doing this then. There is a a large chance that you might get black listed. But thank you for your time.

So if they’re not desperate to sell me something, why do they bother mailing me in the first place?