Reduce Spam by using alternative Google Mail Address ?

[Osiris]

I read about this tip yesterday at Digital Inspiration and when I woke up today I saw that Lifehacker wrote about it as well. The tip mainly stated that users who signed up for Gmail would not get one but two mail addresses: user@gmail.com and user@googlemail.com. The suggestion was to give on out to friends and use the other for all the other signups and conversations on the Internet.
It might seem like a solid trick unless you think about it for a second. If I know that there are two email addresses on those two Google domains that lead to the same user the spammer could know as well and most likely will. So, even though you use one email for private matters and the other for everything else Mr. Spammer will simply add a script that sends mails to both Google accounts automatically.
The only real way that works in my opinion are separate email accounts with no connection whatsoever. Using one account with those two email addresses is simply not reducing the amount of spam that you receive.

Reduce Spam by using alternative Google Mail Address ?