There will always be some high frequency noise imposed unless you're WAY out in the middle of nowhere, I'm not sure why you're surprised. We shouldn't expect anything approaching a clean sine wave.
If you're meaning those seemingly short bursts of high frequency riding on the side of single cycles, it could be anything. The fact that it seems to be synchronized to the power line means it is probably coming from some kind of switching power supply, seemingly basically in a sleep-burst mode, rather than interference from, say, a cell phone, or something that would be more randomly placed on the 60 Hz wave.
I would have to zoom in more with my ancient DSO in order to see anything like that riding on my 60 Hz but I'm sure there is some cruft there.
Just for kicks, this is what my living room looks like this away from any wiring, scope floating:
With the scope ground attached to power ground and the probe near a power bar:
With the scope grounded, probe laying away from anything and me not touching it, so no capacitive coupling from the big antenna (me):
Maybe later I will pull out a good torroid that has some HF capability or rig up a danger-divider and capture what's actually on the mains, just for fun. For now I need to get back to some
Real WorkTM