I'm a Cubs leader and have been for two years, assistant leader before that for 3 years, I really enjoy it but it's getting to a point now that I dread speaking to a parent.
We're probably one of the most active Pack groups in our district, lovely Beaver leaders and super active Scout group, so as a whole there's roughly a two year waiting list, for each section.
It's done by age and a bit by first come first served, Beavers get given priority when moving up to Cubs, so even if a child had their name on longer, once a Beaver turns 8, once theirs a space available it goes to them. It's the same with Cubs moving up to Scouts, the information is written on a sheet that's either handed to whomever is signing them up or emailed to them and yet almost every week I get an email/phone call from parents about the waiting list
To ask questions is perfectly fine, I'll happily answer but today I've been yelled at over the phone by a Dad who didn't realise that scouts have a separate waiting list , so although his DC is almost 10 and has been on the waiting list for a year, it's pointless for the DC to remain on our list as he probably won't get a place until he's past 10 and a half, in which case he'd be too old for Cubs.
I suggested a few Packs they could try and just got cursed at, 3rd bloody time this month!
Normally the waiting list issue wouldn't bug me so much, but one of our Cub Leaders, has had to stop coming down because of her pregnancy and our 2 young leaders are off for exams, which only leaves two Leaders to handle 23 Cubs and all the parents seem to do is complain.
"Why doesn't xxx have as many badges as vvv" because xxx hasn't put in the bloody work! But I don't say that.
"Xxx really dislikes this badge, can't you do another?" No , it's a challenge award and I have 3 Cubs that have to do it to gain their silver, and it also goes towards xxx's silver
"Xxx won't be at the parade because he only signed up to Thursday evenings" and yet he's at every theme park/camp/fun event 
"My daughters brownie troop are so much active then you lot" then by all means volunteer and make it more active
"Xxx says that the kids are too noisy and that makes it hard to accomplish anything" xxx is the worst of the bunch! The kid who stayed under a table for 5 mins and who's Mum I've had to call in multiple times to pick him up early has the cheek to complain about other kids!
I like constructive criticism, it's the only way to improve our troop, but I don't get paid for this, I have a job and a family and they've no bloody right to yell at me, and if you're going to complain, then do it far away from me!