Common trademark scams

How to avoid scams for trademark services (U.S. Patent and Trademark Office)

Recognizing common scams (U.S. Patent and Trademark Office)

Why Did I Receive A Communication From Someone Other Than My Trademark Attorney Saying My Trademark Registration is About to Expire, and other Trademark Scams?

Invention promotion companies and scams

Scam prevention and avoidance (U.S. Patent and Trademark Office)

Invention promotion companies (ipwatchdog.com)

Invention promotion firms (wikipedia.org)

Invention Marketing Scams (Federal Trade Commission)