I guess I just have a different perspective on mist energy than most people. I look at it this way:
He needs his CE to craft something.
I have ME.
He wants someone with ME to tab him.
CE = Permanent, volatile energy
ME = Limited, regenerative energy
It costs 10 energy to travel down an elevator. If I tab him, I'll lose ten mist, but I'll regain it all in about three hours. I don't really have much to lose by helping him.
I have an elevator pass, so I wouldn't end up using the mist anyways. It'd be better for him to use my mist than for me to not use it at all.
Energy is energy. Mist is still value. Not quite as flexible as CE, but it isn't worthless either. In fact, you cannot both do a full tier run and tab someone else on mist alone (missions make this a little different but not much.) I'm saying asking for -energy- gratis is begging, not asking for Crystal Energy specifically.
And there have been since the first week people who spin such stories and never spend their own energy for runs. Crafting items for sale on 'free' mist turns that mist into crowns very nicely, always has. The auction house makes that easier but not quite as profitable. Which is fine... if your 'free' mist is a day you're not playing anyway or an alt-account when you have a paid account. It's not so fine when you craft and auction items first and then go getting other people to tab you onto your runs.
Simply put, there's no way to tell the difference between a naive cheapskate who's simply struggling for his/her next upgrade and someone systematically scamming with the exact same story. Anyway, I don't have any inclination to tab either one, I'd rather like to advise the former to be a little less selfish and to kicik-ignore the latter... but I can't tell them apart so I'll assume the former until proven otherwise, while the party leader you're objecting to assumed the latter. I can sympathize with that too, it does get tiresome.