Can I use cooking sherry instead of red wine in my stew?
"Cooking wine" is unfortunately ubiquitous on US mega-mart shelves. It is notoriously bad. I mean really, really notoriously bad. It starts bad, and then they add obscene amounts of salt so that it can be sold on grocery store shelves for $6.  As pointed out by @Malvolio, "salted wine is supposed to be disgusting! Many US states have special licensing requirements for any store that wants to sell alcohol, even wine and beer, but wine that is so heavily salted it cannot reasonably be consumed directly is exempt." The salt literally makes it undrinkable, so underage and other sales that would otherwise be illegal aren't an issue. The added salt also ups the shelf life, but not nearly enough to justify the sensory assault of these stunningly awful "wines". Canadian "cooking wine" is the same thing, just with different levels of salt just like the 50 states.

(these are just examples, all "cooking wine" brands on US grocery store shelves are the same level of truly insulting):



Skip the cooking wine. Go to a liquor store and look at the inexpensive bottles of wine. You might be surprised - bargains abound.

Incidentally, if you don't generally love to drink wine but occasionally like to cook with it, you might try what I do. I keep a bottle of inexpensive but good dry sherry and another bottle of inexpensive but good dry vermouth tightly capped in the fridge. Those wines, along with marsala, port, and others are fortified with liquor, giving them a much longer refrigerated-after-open shelf life than normal wine. Fortified wine can often replace the wine in recipes, at an equal or slightly reduced volume of the non-fortified wine called for. Sherry is often actually called for in Chinese and other Asian recipes, and dry vermouth can generally sub for "dry white wine" in recipes. 

Cook's Illustrated says: 


  Our recipes often call for dry white wine. Its crisp acidity and lightly fruity flavor add depth to everything from pan sauces and pasta to risotto and steamed mussels. The problem? Standard wine bottles are 750 milliliters, and our recipes rarely call for more than 1 cup (roughly 235 milliliters) of wine. That leaves us with most of a bottle to finish in a matter of days. Dry vermouth, which can be substituted for white wine in equal amounts in recipes, is a convenient alternative. Like Marsala and sherry, vermouth is wine that’s been fortified with a high-proof alcohol (often brandy), which raises its alcohol content and allows to it be stored in the refrigerator for weeks or even months after opening. 


I buy the dry vermouth recommended as the best buy by those same folks at Cook's Illustrated/America's Test Kitchen, which sells for $6-$8 in the liquor store that connects to the grocery store (barely more expensive than the hideous salt bomb on the grocery store shelf).



One of the Sherries recommended by the Cook's Illustrated taste test clocked in at under $6: