Some cyclists are a right nuisance, but most definitely aren't. I did an experiment on the way into work recently (I walk by the way). Out of eight cyclists, three were cycling on the pavement. Strangely, the pavement cyclists were on the pavement in areas where there were cycle lanes. The ones who weren't pavement cyclists were all cycling on the road (where there were no cycle lanes) in areas full of busy traffic.
A few months back there was a period where I noticed a HUGE amount of stupid cyclists:
1 - went through a zebra crossing outside a school, as young kids were crossing. Just went straight through, cutting a neat line between the kids.
2 - about to leave a shop with my 3-month-old son (at the time) and a cyclists is bombing it along on the pavement right in front of the shop doors. Had I stepped out a second earlier (the shop has a step so I would have gone first, backing out) it would have bowled me over.
3 - a cyclist hit my son's pushchair. Yep, actually hit it. He was coming up behind me on a crossing (using the crossing as a pedestrian) and didn't realise I had a pushchair, and cut right in front of me to get to the next bit of the crossing, hitting the pushchair. Fortunately no damage done and he clearly didn't think enough of it to stop and apologise, as he carried on oblivious even after I shouted after him.
As I say, there are some idiots about. There are probably even more good cyclists than idiots (as my experiment proved) but the idiots seem a lot more prevalent.