Been to Venice three times, and never found good food.
We've also been to Venice several times and have only had one bad or disappointing meal.
We generally avoid canal side places to eat. They are usually overpriced and under quality. Especially in the Rialto Bridge area. But there are some exceptions.
There is a canal side place you might want to try near San Marco. Trattoria Da Giorgia ai Greci is a bit pricey (most places in Venice are) but the food was quite good.
In the Rialto Bridge area consider Trattoria Da Marco Valla Fava on Calle Stagneri. It is definitely pricy so you might want to do lunch there rather than dinner. Some of the best sea food ever!! Try to eat inside rather than outside. The place has been around at least 50 years so they must be doing it right.
Also in the Rialto area (on the other side of the Grand Canal on the walk toward Piazzale Roma) is an out of the way place named Pane Vino e San Daniele on Calle Dei Boteri. Definitely a local place, good food, good house wine, and not expensive at all.
If you go to Murano, try Ristorante dalla Mora on Fondamenta Daniel Manin. Lots of locals eat there.
You should be able to check the menus online for at least a couple of them.
If you try one (or some) of those places, let me know what you think.
Ai Mercanti is good.
Al Covo - arguably Venice's best seafood eatery. There are more elegant and upscale restaurants but, the execution, freshness and overall value I think is hard to beat.
Osteria alle Testiere - a small, fiercely independent but well executed Venetian favorite.
Trattoria Al Gatto Nero (Burano)- their popularity has increased over the last decade, while an all-around seafood restaurant, they're noted for their risotto
Torrefazione Cannaregio- arguably the best coffee in the lagoon
My first time there, I would've agreed with you. But the second time I found some delicious gems.
- We Love Italy Fresh Pasta: handmade fresh pasta with delicious sauce of your choice. At the time it was 5euro for one dish and it was so, so tasty.
- Alaska Gelato: One of the better gelatos we had in our whole month-long trip. Very, very good.
- Cicchetti: You can get this all over venice but I found the best places to be closer toward the Cannaregio area
- Osteria al Garanghelo: Best branzino I've ever had. The service was delightful. It was a charming, small venetian place. All four of us loved everything we ate, which is no small feat.
Just some ideas to try in case you head back.
Non-fancy but good places to eat from 10-day December 2023 trip:
La Rampa in Castello (also on previous trips))
Osteria La Zucca (also on previous trips)
Osteria da Pampo in Castello
La Palanca on the Giudecca
Very Good --- canal-side in Cannaregio and very good
Ca’ d’oro alla Vedova (how they spell it on Facebook) just a few feet off Strada Nova but pretty good —- meatballs.
****With one exception, all are far from San Marco, the Rialto bridge, and the Strada Nova. Our restaurant choices are influenced by my hating seafood. And on this trip, we had our grandchildren with us.