Why am I always playing opponents rated lower?

I'm rated around 1650 in live blitz.  I have the minimum opponent rating in live set to my rating - 100 with no upper bound.  But 90% of the time I find myself playing opponents rated below me... often almost the full 100 points below.  This is getting on my nerves!  Do all of these people have the minimum opponent rating set to their own rating or higher?  Don't they realize if everyone did that no one could start any games...

I agree entirely with you - at least 9 out of 10 are lower than myself. I think on one hand it show a lack of generosity of spirit BUT on the other hand playing lower rated opponents can be useful because it forces you to continually pay attention and perhaps deals with earlier opening deviations , often not "good" but demanding close attention. It surprises how often lower rated players are awful in the opening but tactically naturally very resourceful.

Same here. The reason is simple: there are much more lower rated than higher rated players. Setting no upper bound doesn't help because most players (including yourself) don't accept opponents much below themselves.