HIV can live for as long as the fluid stays fluid and temperature stable. It doesn't die instantly on air contact. Temperature extremes can cause it to die faster or stay alive longer. If it's still fluid, assume the sample might be infected. I think the legend of HIV dying instantly outside the body stems not from the virus but rather from the reality that the virus has no easy path into your bloodstream from the outside, where as it is pretty easy when being squirted into your body. But if you had a fresh cut and it came into contact with relatively fresh blood or semen, yes you could be infected. And as others noted, other infections can downright thrive in your extra-hominem fluids.