I have seen it carry mites. It shouldnt kill your snake unless it injests it. I do recommend newspaper, carpet, or cypress mulch over it. Tell the guy not to use it if he thinks it will kill his snakes or ask him for the reason it will kill your snake...many people hear something and tend to over react. I once purchased an under cared for tiger reticulated python from a guy who would not allow me to probe the snake before buying it because I could "pop the membrane." I showed him my probes and explained I would use a larger ball point probe and apply almost no pressure. he still didn't feel comfortable so I felt in somewhat of an awekward situation. I took "her" anyway since she was 7 ft and roughly as big around as my wrist. I kept her quarantined and she ate great for me (so it was pure neglect on his part). I ended up probing her under my care and she was female as well. However, my purpose was not to keep her (unfortunately because I was falling in love with this animal) and I found her a better home. The person who got her from me was extremely excited and explained the enclosure he already had for her, he took my email and gave me his and said I could ask for photos of her at any time to see how she is doing since I was extremely picky on who I would let her go to. Anyway, there is not much point to all this besides the fact its an alright story and it shows you that people who cannot explain why something is wrong are not people you can likely convince on something anyway. i will also use this post to mention the guy I got the retic from had a 13 ft burmese in his basement he would not let me look at (and I am sure you all know why). He was not interested in selling her because he has had her so long but I would love to get her out of there sometime. And since this post isnt already long enough...I can add the retic did have one bite mark on her from the burmese which was housed and fed with her. So I guess the story isn't a full happy ending..just a happier one since he is one less giant snake in his care. So did that answer your question on reptibark? lol