When you submit a trademark application it’s reviewed by a USPTO examiner who determines whether the mark meets the legal standards for registration. The requirements are exacting and it’s not unusual for the application to be rejected on technical grounds. Here are some common reasons.
The specimen is not acceptable. The specimen must show the trademark being used in commerce, i.e. how it's presented to the public. A company website screenshot showing the mark with the associated product or service is typically sufficient. If the specimen is rejected, email a proposed replacement to the examiner to see if it will be approved.
The mark is “merely descriptive”. You can't register a trademark that simply describes the associated product or service. For example, “blue jeans” probably couldn’t be trademarked for dungarees. Adding a prominent graphic element can turn a merely descriptive mark into one that passes muster.
The description of the graphic element isn’t acceptable. You must provide a detailed description of the mark's graphic element on the application. The examiner may refuse registration if yours is insufficient. The Office Action often suggests an acceptable alternative.
A disclaimer is required. You may have to disclaim the right to the exclusive use of certain words. For example, if you apply to register “Pigeon Nose Solutions”, you might be required to acknowledge that others can use the word "solution". It seems obvious but the disclaimer may be required under trademark law.
The mark cannot be registered. A “substantive refusal” means that a mark cannot be registered even if the application is amended. They often occur when the examiner believes your trademark is too similar to another already on file, i.e. there is a "likelihood of confusion" as to who is providing the good and services. These determinations are highly subjective and it may be better to redesign your mark instead of litigating the issue.