There is such a thing as bad traffic. In fact I would argue that about half the traffic most sites get could be considered "bad". For instance if you are selling computer tables you might be getting traffic related to computers or to dining room tables, etc. These users will most likely bounce back to Google since you aren't selling computers or dining room tables.
There is growing evidence that Google and other search engines are looking more closely at how quickly visitors bounce from your site. In one way this helps you, it means that your site is less likely to show up for those irrelevant searches. In other ways it could penalize your entire site since Google could see it as your site not being user friendly.
People usually bounce for one of two reasons- content and usability. If the content isn't what the user wanted they will head back to Google- keep in mind content includes product prices. If the content is there but buried, or the site is a mess with no clear calls to action then they will bounce back to find a better page that serves their needs. Remember that most visitors don't care about you, they don't know your company or why you might have a better product or service.
So the key is building a site that attracts the right kind of traffic. When we do keyword research we look at search volume and we consider "commercial intent". Basically this means that we want to get our clients listed for relevant industry searches that have users with high commercial intent. The "wallet on the table" user. Ready to go once they find the site that meets their needs.
So when you look at your Analytics and you consider your site traffic, whether it is rising or falling, look a little closer. Make sure you are looking at things like time on site, bounce rate, pages per visit etc. Also look at keywords that brought the user to the site. Are they relevant for what your company or organization is doing?
If you aren't getting "real" visitors but only "lost" visitors then your website isn't doing its job.