I agree that online and print should be treated the same as we are doing the same job - just in a different medium.

Personally, I only review what I like regardless of whether I bought it or someone sent it to me for free.  I try to indicate if I received it from someone but as you mentioned, it's our job to be on top of the latest products and it would be impossible to purchase it all.  It also becomes a bit redundant if every post starts with "I got this for free from XXX" and that can come off as braggy to the readers.  You are right to say it would make no sense to send it back as that is just not sanitary.

I don't review everything and certainly never out of obligation and never for compensation.  We stick to our principals and are open with our readers and that's what matters the most.