We’re required to disclose any form of compensation when writing a blog post, which has led to all sorts of stresses, excuses, legal discussion, and bloviating by bloggers.
It’s really easy to do proper, simple, legally-compliant disclosure:
Just write a sentence at the start of each post explaining your relationship to whomever is compensating you or giving you free stuff.
Here’s a perfect example from a post on Mashable:
That’s all it takes, it’s not a big deal, and you need to be doing this. No excuses!