Hey they havent sent me such a box! I feel left out! Haha!
In all seriousness though, I never had a feeling they were expecting somehting back from me. On the contrary even.
I too receive samples, or sometimes even bottle(s). The tatsing notes section is very popular on my site, and producers like to see their (new) products presented there. When I receive something I occasionally even sent it to one of my regular contributors for them to write a tasting note off. That way its in the hand of a third party even.
PS, when I sent samples away to third people, I do try to think of their preferences, and sent samples to those people who I'm pretty sure of that they will like this particulair expression. Not to favour the producers, but becuase this is my way to say thanks for the contributions to the database.
Also, I have noticed that I only receive the really nice stuff. I guess that's their way to prevent tatsing notes that are less beneficial to them to enter the database...
But I never had the feeling they expect for me to favour them when writing a tatsing note or anything else. BTW, when visitting distilleries and so for the virtual reality section for example, dont forget you're giving them an excellent free 'advertising'. When you make mention of their products in your podcast, your giving them free advertising as well. If they give you soemthing in return for it to enjoy, while keeping your indepence in high regard, I do not see anyting wrong with that. Our hobbies (podcast for you, site for me) in general are beneficial to the whisky industry.
In fact, its part of the fun, for me at least

I get to taste stuff I would never be able to buy this way!