One of the big things I hear about (I work at Dish, in a call center) are the customers that sign up through a retailer, and aren't correctly informed of the $49 charge a lot of retailers charge to set up the account. They are supposed to disclose that to customers...but customers either forget, or are misled.
I also, over time, have dealt with a lot of customers who were told big stories by retailers, about what channels their package will have, or the actual monthly costs. I've also heard about our inside sales people not disclosing proper info, but not like I hear about the resellers.
All this said, this is likely not going to apply to the good retailers/resellers. I can just say, the majority of the bad complaints come from 3-5 of the biggest resellers, two of which send most of the junk mail flyers that come with the coupons I get in the mail, or in the Sunday paper.
(Disclaimer: As a Dish employee, the opinions here are my own, and do not reflect the opinions of my employer)