I don't review beer, liquor, etc.  I enjoy drinking it, but don't think very deeply about what I'm having.  I also probably would never review my bank, credit cards, insurance, etc. because I am financially-illiterate and let my husband deal with all of that.  All I need to know is that the card will work when I use it to pay for something.  =)  I probably would never review a TV or sound system either simply because I don't know or care about the details that consumers who care enough to read reviews want to see. 

I have written about my car, my GPS, my TiVo, my iPhone, etc. so I have broken out of my Pets-Beauty-Cleaning Products comfort zone... a bit.