Will Stahl-Timmins gave a great talk to the IIID last week (International Institute for Information Design). He is the data graphics designer for the BMJ, a leading medical journal.
Almost as an aside he mentioned the issue of trust: well-finished graphics in a medical context can sometimes be mistaken for marketing by pharma companies.
Integrity can be a problem for infographics, and I've mentioned it before: infographics which round the numbers up or down too much, or which haven't been proof-read against the data, give graphic design a bad name.
Over-simplification is the main objection the plain language movement face. You don't often hear it mentioned in the context of graphic design - perhaps that's because no one actually takes us seriously enough.