Like anything made by Microsoft, Windows servers are loaded with code. You’ll typically find that many web hosts will offer a free website building tool with your hosting package. A great deal many of those are Windows-based. They suck. Don’t use them. Your website will be littered with code, making it difficult for the search engines to find the meat of your content so that they can index it properly. You are much better off using a LINUX or UNIX server. When interviewing your web host, ask them if their servers are LINUX or Windows-based. If they say Windows then shop elsewhere.
Windows servers and ASP go hand in hand. Why? Because they are both Microsoft products. If you guessed that ASP is littered with code that bogs down your website, you’d be right. Just like the Windows server, it’s got all kinds of useless code added in that makes it more difficult for the search engines to crawl your website. Build your website in HTML. It will get crawled better and will be more likely to get indexed by the search engines.
The answer is it is only bad for certain use, namely, as a navigation menu. Yes, your navigation menu will look cool and your users will love the flips, turns, drop downs, flashing giggles, and other bells and whistles you embed into your website, but the search engines won’t crawl those links and your internal web pages won’t get indexed. And that’s why I recommend, instead, that you use an HTML navigation menu, because the search engines have no problem crawling HTML links.