You never want to infringe on trademarks. In addition to being a legal violation, it seems doubtful that any business would want to be viewed as unoriginal. So what happens if your business creates something that is slightly similar to an item that has already been trademarked? Fair use applies to trademarks as much as it does to copyrights. But you still have to be very careful or you could end up dealing with complicated legal issues.
Descriptive Use for Ordinary Words
A business might want to use a particular term for a product that sounds similar to another trademarked name, yet might be so common that it falls under fair use. This pertains to ordinary names and using the name of a real person when it's subsequently trademarked as a product elsewhere. General terms might be used to describe something in a marketing campaign for your business. You can use those, even if someone happens to be using it as a trademarked business name. The key is it has to be describing something rather than being used directly to sell goods or services.
Nominative Fair Use
If you work in the media industry, you can refer to certain trademarked names in an article or other piece without being sued for infringement. That's because you're only using it for commentary purposes. You can also apply this to parody if you happen to be a creative business that publishes comedy or satire.
Some complications have arisen from this fair use law, particularly in the use of company logos in online articles. Many online publications are starting to use company logos in their articles as a descriptor. When the commentary becomes critical, some companies have taken offense and asked their logos to be taken down. It's an issue still being formed as fair use on the Internet continues to have contradictions.
The Contradictions of Non-Commercial Use
Trademark infringement cases can sometimes argue that even if the use of a trademarked image was for non-commercial purposes, it can still be considered infringement. This can be stretched to include promoting another business on a tribute website for another trademarked business. These sideline arguments of infringement can make sense from the outset, even if they were perhaps unknowing in their intent.
It's why you always need guidance when working with intellectual property and using existing items you think might be trademarked. You should never assume anything when it comes to usage rights unless you are absolutely sure. If you are planning to use the works of others in any context, be sure thay you have done research on any regulations or have consulted with a legal professional.