Let sleeping dogs lie.
Story: There was a thread recently where a guy was asking about whether bleach killed Hep C. I pointed him in the direction of research showing that there are doubts about whether it does outside of laboratory conditions, and as most OD'ers know Hep C can survive outside the body much longer then HIV. The poster revealed that he had injected with an old needle that his Hep C infected friend had used before; he had used bleach to clean out the needle, and he began freaking out about contracting the disease.
I asked him why he didn't use fresh rigs, and he explained that he doesn't know when he's going to score and when he does he can't be bothered to get new needles just for the rare occasion and so shares. 8)
Moral of the story: If you are going to be injecting, it's a good idea to perhaps buy clean needles and other supplies in bulk and stock them.