Grocery Store Samples?

I don't know about Costco but Trader Joe's always has the packaging available. I normally just log it as 50 calories per sample and call it a day.

It is a sample of a product they are selling right? Ask for the nutritional info or find the package.
If the total amount you eat is equal to a large snack or small lunch I'd think 300-400 calories might be a better guess than 200.

I don't shop where they give out samples like that. I would probably sample 1 item and pass on the rest.

I just guess, which is pretty easy to do accurately enough (not perfectly accurately) after some logging experience: I know what an ounce of chips, crackers, cheese, etc., looks like, and the calorie variation in a category isn't that much.

If I'm not sure, I'll guess toward the high side. I'm a believer in accurate logging, but also a believer in not jacking my life around in unpleasurable ways for the sake of avoiding occasional calorie inaccuracies. To me, sampling is fun.(I am more likely now to skip less interesting items as not worth even the few calories.)

In my case, sampling is only once every week or two, besides. I'm not at Costco daily. If I'm off by 100 calories, even - which is unlikely - that's lost in the nose of other minor eating/activity calories in a week. YMMV.

Scan in the package, then figure how much of the serving you had. You can ask the associate how many samples they get from the package. Even if it's a rough estimate, it's better than not logging. (Most of the time you are getting 1/8 a serving, used to work at a store that gave out samples, we were instructed to cut each item so that we would get 8 pieces per recommended serving, don't know if this applies to all stores though)

I don’t usually eat the samples but I’d just make my best guess. Maybe 50 calories per sample.

How is this any different than eating at a non-chain restaurant or at someone else's house? Other than the fact that you're eating very little so guessing probably isn't going to be a problem? If you eat YYY at a restaurant you have to guestimate the calories, right? You aren't going into the kitchen while they are cooking and weighing all of the ingredients. Just do the same thing. Ate a bite sized sample of YYY at the grocery store, just find an entry on MFP that seems relatively close and ballpark what fraction of a serving you ate.

You can't be accurate, just be reasonable.

The grocery store I shop at most has samples of produce often. Squares of cantaloupes, slices of apples, strawberry slices, etc, speared with toothpicks. They are legit samples; when the fruit isn't ripe the samples are not very good. When they are ripe, I could stand in front of the melons all day. But I don't. I buy one and take it home and weigh what I eat at home. But when it's just small samples of produce, I log it as one of the fruits in a small amount that seems reasonable. I rarely try other samples.