Venice

No odiferous alters reported recently.

Is that a typo, and what currently shows as “alter” was intended to say “water?” Even 20 years ago, some canal water would have a smell, from decaying aquatic plant matter. Haven’t been there recently, so I can’t give you a current report, but In some ways, high sea water can help rinse out areas where the water wasn’t moving so much.

Been to Venice 3 times in February, never noticed an unpleasant smell from the canals. Smoke outside the bars is another matter . . .

I have been to Venice many times, but never in January or February (too cold for me, I already live in England which can get pretty chilly in winter so I have no interest in churches so cold a heavy coat makes no difference, so we go to Monaco and the Riviera if we go anywhere in February) so I can't speak directly to February...

But I've never encountered any unpleasant smells around any alters, and I've never detected any sewage in the canals.

Like all waterways in the world where cruise ships go and other boats there is always a degree of pollution from bilges and spillages but nothing that would bother me.

It is unlikey you will be in the water in February.