Most of the time, spam emails you receive in your Hotmail account are automatically caught, filtered, and placed inside the junk mail folder, instead of remaining inside your Hotmail inbox to clutter it. This allows you to concentrate on legitimate email messages, and not waste time sorting through junk emails to get to your contacts' messages. But what if a spam email is not filtered as junk mail? This tutorial explains how to make sure that these emails are reported, and don't stay in your inbox.
The next tutorial explains how to report phishing scam emails, where the spammer tries to trick you into revealing personal information and/or sharing your password for sensitive sites (like PayPal, eBay, your bank, etc.) This is a special case of spam.
For "regular" spam emails, follow these steps:

Next, learn how to report one or more emails as spam without having to open it / them:
Hotmail also lets you report a spam email as junk mail without requiring you to open the message itself:
When you see that an email is clearly spam (for example when you get emails in a language you don't understand), you can in most cases safely assume that it is junk mail, even without opening the email.
In cases like these, just right-click on the email message, and choose "Junk" from the context menu.
This approach is completely equivalent to the one explained earlier, and the email will be marked as spam, reported to the Windows Live Hotmail team, and moved to your Junk folder.
Tip: Windows Live Hotmail now gives you the choice whether or not to report spam when you mark an email as junk; we recommend that you keep this default option enabled, since it benefits all of us Hotmail users, by allowing the Windows Live team to make their junk mail filters better! For more details: customize Hotmail spam reporting + configure junk mail settings.
The answer is "No" - Hotmail automatically updates its junk mail filtering system based, in part, on the reports you and millions of other Hotmail users make when they come across junk mail and report it as spam.
This is why it is important to report spam emails when you get them, instead of simply deleting them - obviously, this remark only applies for junk mail inside your inbox, that was not filtered - anything already inside your junk mail folder shows you that Hotmail already knows that these messages are spam!