Sorting very odd

It seems the sorting is wrong because new topics appear part way down the list. This is for guests, so the users prefs aren't relevant. I've cleared the cache, so it's not that. For example, the one for "Marriot Hotel with the twin towers" was the newest posted here. Is it my understanding that's incorrect?

This was caused by me not understanding tags order, so I'd set a different value to each one. I put them all to 0 and the sorting order is now as expected.