Not all fraud is committed knowingly, which is why it's so important to defend yourself if you're accused of a crime. Your attorney is familiar with situations like yours; maybe you used a credit card and were accused of fraud or were mistaken for someone who is known for credit card fraud. In any situation, the right defense can help you protect yourself.
There are some ways you could be committing fraud without realizing it. For example, if you use someone else's credit card without permission, that constitutes fraud, which most people understand. However, if you have permission, you could still be committing fraud and the terms of the cardholder's agreement.