Taste-testing is a perfectly acceptable cooking practice. It's necessary for adjusting seasonings and making sure what you're serving is not only edible but tastes good! Just keep it to a sip or tiny taste here and there. Otherwise, if you're drinking the rest of the wine bottle after putting a bit in your recipe or taking multiple bites of food before serving, you end up taking in a ton of extra calories before you've even sat down to your meal.