Could ren be be tinted with other emotions or feelings besides bloodlust and malice?
Could you tint ren with say love or arousal to seduce a target?
Or indifference to make them ignore you?
I honestly think its possible but such an extremely high level nen technique that only top tiers like netero or ging can use it.
I think thats how netero hides his enormous power from other nen users. Hisoka could feel illumis aura without even looking at him and your telling me he couldnt have sensed neteros.
Also ging has one of the worst personalities to be a team player yet he can get into teams like the original archeologist team he got into or the way his greed island friends still do his work. I also think thats how he got into the dark continent expedition team.