False pretenses stink.
Some people come straight to you as a contact. Others, pretend they seek friendship. If you're in a position to help someone, there will be users. It hurts.
Social media has lighter incidents. Someone you contact blasts you with promotional email. Someone follows you on Twitter, baits you into following back, then deletes you without a thought. These instances aren't outright duplicity, but they're shady...
The networking "rule" is to give first so others will reciprocate our kindness. The basic thought behind the rule is fine but, when people start giving in expectation of return, it's wrong.
When I comment on a blog post, I liked the post. When I retweet, I found something of value I want to share. I don't ever... ever... do the social media activities people associate with kindness expecting to be repaid. If people follow me, retweet me, share a poem or short story I wrote... I want it to be because they see something of value in me or my work. It doesn't feel right to gain attention through obligation. And if I come to you in friendship, it is genuine.
Then again, what the heck do I know? I'm probably the worst person at networking the Internet has ever seen.
Do you think it's okay to expect a "return" when you reach out?