Not offended at all. I find the Yarn Harlot to be witty and entertaining and yarn porn.....well sometimes the money I spend on yarn is obscene and I do lust for yarn!
Different strokes for different folks, if someone offends you then don't read it. If an expression bothers you, don't use it. There are so many real problems in the world I can't get upset over literary expression. An alternate meaning of the word "pornography" is the depiction of acts in a sensational manner so as to arouse a quick intense emotional reaction. Harlot has many meanings; It is a Middle English word, rogue, buffoon, female prostitute, from Anglo-French herlot beggar, vagabond .
It's only offensive if you chose to make it so.