I try to be honest, but also find if (if there is an if) things that other people might like. For instance, I didn't care for the
Tantus O2 Mark or the
Triple Orgasm French Kiss Rabbit Style Vibe but I found things that other people might like about both of them. There are things about both of these toys (especially the Mark) that I simply know other people would like, and the Triple Kiss had some unique features that I also know some women could get behind and really love. So, I made sure to focus on those good things, while still giving my opinion about why it didn't work for me and why. But, I didn't focus exclusively on the bad things. One person's least favorite toy is an other's fav.
If the toy or product seems a real bust to me, I'll try to use humor without bashing either the item or the company. I wrote a review for a lingerie set
Erotique Butterfly Babydoll that I though was really poorly made and might not fit too many people, so I made the review humorous, to still write a good review from it.
I find its still easy to describe the item in detail and then go on to tell why it simply didn't work for me.
Good luck.