It depends where you sit, really. Usualy, i am not killing even sentient creatures who atacked me. If i can, i am just running away, when i can't or just doesn't want because i am with companions, i just beating them to uncorsious or forcing them to flee. My companions are killers, not i. Am i moral? No, i am robing those who tried to robe me. Just wresle out their weapons and shields, if i have better equipment, i just throwing it on tree or to river with hippos... or some other spots and go away, when They have better equipment then i and my companions... i just keep it.
I usualy play as peasant, who left his village because some crime. I do not know, he abused some woman, she beated up her father/mother or killed some noble. Sometimes They start adventuring because my last adventurer has been badly injured and... They giving him last blow into head or killing him without pain during his sleep and disapear (this is main reason why i play as elfes or goblins).
Humans usualy doing adventure like things. Is striping to naked enemies soo inmoral? Meybe, but this is usualy only way to force them to not chasing me when i allready beated them two or three times.
But my humans are most of the times focused on hunting down night creatures... then just settling in some nice hemlet or ruined city and because They are fameous, They are after some time leaders of fractions. Hunting for night creatures as peasent is nasty thing, you are fighting with opponents better than you, so a lot of flames is related there. A lot of gore and blood is related to hunting.
Vampires are just victims, in my opinion, so if They run away, i am leaving them (if They are not my target). If They not... i am collecting Theis blood and storing it in some easy to go place. I am tring to give them clear death, as fast as possible, just because They are more powerfull than i. Sadly, humans are not drinking from wells in towns, even if you wait there a lot of days, so there is no real way to spread vampirism.