#1. The lack of professionalism and common courtesy of returning calls, e/m's or tx's in a RESPECTABLE time frame! -especially when working a deal and "Time is of the Essence" for ALL of us!
Here's my #1 and #2 pick: http://www.trulia.com/voices/Home_Buying/Foreclosure_short_s
There are millions of home sales that go together every year with everybody being happy-ever-after and are brokered by professional real estate agents, but this is often overshadowed, not just by by the rare - remarkable, even - transactions where brokers draw formal complaints and some sort of disciplinary action, but from the petty jealousies ("s/he'll just take any listing that comes their way," for example) and fueled by negative impressions such as Trulia's Q&As that ask, "Why can't agents return phone calls on time?"
Real estate is a unique industry. We are professionals, licensed by the state, to sell the biggest ticket items people buy - real estate. We are compared to automobile dealers, as if $17,500 for a Kia is on a similar scale as buying a home or investment property.
We like to compare ourselves to physicians and attorneys, which is silly. I think we're closer to fine art dealers, except that our clients don't have to leave their property with us to get it sold. Also, they grab 25%-35% of each sale, whether it's a $50,000 piece or a multi-million dollar masterpiece.
It's true that the bar of entry is low, but mastery makes a big difference and takes time and experience.
I think that my number one complaint is that too many agents think we're not as good as we are, and aren't shy about sharing that opinion.