I just don't get this. I've run this mission with 6 toons on live and with another 5 heading back to beta. I've never failed to get infected within 1 minute.
I'm not trying to say anything against you, I just think people (in general) over think this mission. They run all round and don't get infected and wonder why. It's really not that hard. Run right up the pipe in the north, leave your companion on passive, and engage the red rakgoul by the tree. Stand there and let him hit you (occasionally, I've had to use a med pack while he's hitting me) until you get infected. It's worked for me every time.
You're right...it's not that hard AND you don't have to over think it. BUT, I've done all the things that you said..it's only common sense. But RNG can sometimes be a pain in the *** I commend you for being able to complete the quest, multiple times, without any problems...that's some luck you have!
And yes...I'm still trying to get infected! lol I'll keep trying though!