Oooo okay, one to add today:
I went away to Wales to visit family the last two days. I left late on Wednesday night, after saying bye to my hammies - making sure they had enough food and two waterbottles each (in case of blockages), checking all doors were securely fastened and lids on tightly - and returned at midday today.
I had a quick check in the cages (well, Frankie's cage, Pickle and Davos' bins), checked that food had been taken and waterbottles still flowed. All was well. No rustles from Frankie or Pickle, but that's usual for them; Davos popped his head out to see what the noise was about.
So, I sat down at my desk (the hamsters are all in my study) and turned my computer on. Fast forward 2 hours and I feel a tickling on my foot.
IEIEEEEEEEE, SPIDER! I think... but no.
It's Pickle. He climbed on my foot, looked at me as if to say, "What?" then waited to be picked up and put back in his bin.
I have NO IDEA how he got out. The mesh lid is still on and fastened at all edges, and aside from that, the sides of the bin are more than three times his height when he stands on his back legs!
So my vote stands: Hamster escape is somewhat preventable - try as you might, and secure as you think they might be, hamsters will sometimes escape their cages, despite precautions! And totally confound you in the process.
Needless to say, his bin cage is spending the next few days in my bathtub until I figure out how he got out!!