Ok, here comes PhreeX, givin you the straight dope on IV use.. call it "real world IV drug use" ..
In an ideal world, everyone would follow the Guide to IV Drug Use (found in the FAQ forum), but the reality is that most don't - they will break rules, most are with little risk, some are not...
First, for cleaning your gear (spoon/cooker) .. I agree - use straight bleach.. none of that sissy scented color safe shit, get the generic bottle of "BLEACH" .. you can also use isopropyl alcohol.. first clean the spoon, then either dip it in the bleach/alcohol or fill the spoon/cooker with bleach/alcohol ... not many viruses can survive that long outside the body for very long, for instance, say yer sharing a spoon with someone with AIDS - they used the needle already and didn't clean it, so that needle has the virus on it.. well, they then draw up from the spoon and fix - even if you didn't clean the spoon properly, the chances of you contracting something are VERY SLIM .. if you clean the spoon with bleach/alcohol, it should make it quite safe... also, run it under hot water .. the virus couldn't survive all that..
But why not just use your OWN SPOON? It's so much easier.. it's safer, plus youdon't have to wait on someone else to finish first, then clean it up... ITS A SPOON FOR GOD SAKE, THESE ARE NOT HARD TO FIND!
PLEASE, try to follow this simply rule - DON'T SHARE YOUR GEAR .. any fellow junkie will have their own setup..
You CAN use a needle more then once.. why shouldn't you? Simple, when you're working with a 29g needle it's so fine that it will dull fast - the simply act of braking the skin dulls it... yeah, it's sharp enough for 3 or 4 shots, but a dull needle can cause damage to your veins... sure, it's not really major - but it's NOT A GOOD PRACTICE .. another reason is bacteria - you have taken a sterile syringe and introduced body fluids as well as chemicals that contains god knows what - even if you "flush" the syringe, bacteria can fester within... even water can go stagnant, so if you flush the rig with water then push the plunger down, there is still ware atthe head and in the needle.. again, using the same rig a few times most likely won't cause you any real harm, but nothing feels better then a new, new needle... they cost less then a quarter each, WHY reuse the same syringe?
In over 4 years of IV drug use, I have rarely used the same rig more then twice - and when I did it was because I was a meth junkie that just wanted to fix.... but with about 2,500 IV injections, I have NEVER, EVER, EVER shared a needle... I will go without the drutg before I share a needle, I don't care how much bleach or acid you run through it...
Look, IV drug use carries a lot of risks, and while you can get away with doing a lot of shit you really shouldn't, why not do it the right way? As they say, and ounce of prevention equals a pound of... coke or something...