I've had lots of noise trouble with light dimmer switches, touch-lamps, motion-sensing switches, and dusk-to-dawn photocell light controls.

The latter two devices seem to be prone to making radio noise if they use solid-state switching to the control the AC line power (SCRs, triacs, etc).  

Each time I found one of these noise-makers, I either added AC-line-rated bypass capacitors on the input and output lines (which usually helped but did fully eliminate the noise) OR I replaced the unit with one that uses a small relay to switch the power to the load (which eliminated the noise completely).

Link to one of my presentations on radio noise problems:

Link to video of live radio-noise presentation: