It's an interesting reaction. "I didn't bother looking at the studies, but I bet the doctors who studied this didn't realize that correlation != causation, didn't realize that Sri Lanka had a civil war, didn't realize Sri Lanka's economy was growing, etc."

It's worth keeping in mind when people wonder how there could be so many people who reject certain scientific findings. A lot of the time it's a similar attitude - "I'm not going to bother looking at the studies, but I'm guessing the people who studied it didn't think of the problem that immediately cam to my mind, and as such their results are probably wrong."