I just wanted to add my 2 cents on the subject and say that I know this isn't a new phenomenon, myself and many other tatting designers that I respect have experienced many different similar incidents. I often design using vintage and antique patterns as a jumping off point and maybe that is a gray area, but what's not gray is stealing patterns and counting stitches from modern designers who can easily be contacted for permission.
So please think twice before you copy a piece from a picture online or share an un-sourced,clearly scanned pattern or image on Pinterest.
Designers work hard on their art and many like myself earn our income this way. Sorry about the rant and please do check out Martha's post for an excellent post on the subject.