Y’know, that’s a good question. I don’t particularly like throwing away the bags either.
I do re-use bags from the freezer - like, open 'em up, take out a couple chops/brats/whatever and re-seal. I’ve never tried it with the sous-vide bags, though.
One issue is that, at least for my vacuum-packer, to ensure a really good seal, I need a fair bit of extra bag. Whereas a small crinkle in the seal is OK for freezing, it could potentially ruin your sous-vide by allowing water in, so I end up with at least a couple inches of extra plastic. I also double-seal anything meant for the sous-vider. Once the bags are cut open, they’re that much smaller. So even if they could be re-used, I’d worry that after one or two uses they’d be way too small. But that’s my vacuum packer - it’s at least ten years old - maybe newer ones are more efficient?
As far as boiling them, I’m guessing they’d stand up to that. Sous-vide in itself is much lower temperature than a boil, though.
Bacteria-wise, I don’t worry too much. I did at first - especially since the very night I did my first sous-vide, I ended up with the most violent stomach flu I’ve had since I was a kid. I though that I’d poisoned myself with the sous-vider for sure, but I found out shortly afterwards that it was a flu going around town, probably caught from my brother who’d had it a week before I did. <whew>
Anyway, the sickness prompted me to really question just how it is that you can cook a piece of meat at 150 degrees for 12 hours and not end up with a bag o’ bacteria, and the answer is that long exposure to semi-high temperatures does indeed kill harmful bacteria. There’s an FDA publication here that gives time and temperature charts for various foods. The standard advice about “cook all poultry to 180 degrees” (or whatever) is talking about instant killing. Longer exposure at lower temperatures does the same trick.
I’d worry about grease as well. I’ve found that any bit of food or liquid on the inside of the bag can cause a bad seal. And the last thing I want is to open up the sous-vider and find that the food I’ve been cooking for twelve hours is all waterlogged.
Good timing on this thread. I’ve got 28-hour ribs in the sous-vider destined for dinner tonight.