Here's a recent and fairly pro-eugenics survey of all the results they could find showing a reduction in IQ:
And even they basically are only at the stage of saying "maybe there's a hidden trend, that's obscured by other trends moving in the opposite direction" (they think society becoming more abstract has caused a false rise in IQ, due to IQ tests measuring that socially taught facility with abstraction rather than raw intelligence, this may have disguised an actual drop in intelligence).
So maybe it does help to have a preconcieved cause to spot this hypothesised trend.
Regarding their hypothesis, it's kind of a philosophical question about whether you'd rather have a society full of uneducated bumpkins (not sure there is an english word for someone with raw intelligence but no education) with sharper reflex times or ability to discern colors, than a modern post-graduate who scores slightly worse on those tests but better on IQ. It's also somewhat unlikely that the former is going to be having less children than the latter, so they whole dysgenic thing seems to be on shakey ground.
Unless all the people I personally know are very unrepresentative of society in general I have a hard time believing that there is not a negative effect on IQ due to differential fertility.