I agree with what you're saying KSMan. I admit, I have swabbed the needle and reinjected with same needle before as well. I did say that it should be ok to inject twice with a single dart, but as a matter of personal preference, I tend to use a completely sterile one each insertion.
I remember when I had some botox done, and the doctor injected multiple times with the same needle.
But skin and subcutaneous shots, as per diabetics, are easier to deal with infection-wise because they are closer to the surface. The skin is better equipped to deal with bacteria than muscle tissue.
Injecting IM, you are driving something deep into the body and that is where I'd prefer not to take any chances with infection.
The plug of skin cored into the needle, if you reinsert multiple times, you will inject multiple plugs. At least with a single use you only get one.
Having said all that, I still throw caution to the wind sometimes, but maximum cleanness and safety is a matter of preference. It's kind of a psychological thing as well because then at least you know you've taken maximum measures.
I mean, a junkie would pick up a needle off the floor, swab it and stick it in their vein, and 95% of the time probably still not get a bacterial infection (viral ones are another matter). However it's that small percentage of risk factor that counts.
How the hell do you push T oil out of a 29g insulin syringe?