I have read that a low CTR can lead to smart pricing. Does anyone if this is the case and if so does it go by your overall CTR or is it channel by channel?
Yeah, if a nice percentage of those clicks don't convert theres a good chance you'll get smart priced.
Smart Pricing is direct related to Conversions. If your traffic isnt converting great for advertisers, they will report the conversions to google and eventually you would get smartpriced
It's actually more likely that high CTR causes smart pricing. (Too) high CTR means that you are able to get clicks when people are not REALLY interested in the ad. Maybe you trick them with placement, images or something like that. So you get high CTR but people clicked more based on emotion than really wanting to buy something. So your conversion is low and Google adjusts the price advertisers pay for the click.