Offer Description:
At this writing Costco does not yet have a dedicated section of their site to showcase free sample offers, but a very simple search of the site will turn up any current offers.
How to get the free Costco offers:
You can use this search link or just visit the Costco site and type in your own search. Just the word sample or the phrase free sample should do it. If they have any current free sample offers they should show up in your search results.
Direct Links to Current Costco Offers:
Ziploc Bag SampleOffer Availability:
The offers on the Costco site are US only. Some offers may ask for a Costco membership number, but so far, the request forms I have tried allow you to leave it blank. Offers will change over time, and there may be times when there are no free samples being offered.
What are risks in requesting free offers from Costco?:
The Costco offers that I have seen so far have been made through StartSampling. I've never had any problems with excess junk mail from StartSamplling or Costco. They both have very reasonable privacy policies.