IF you are in a regular location, and/or have a good selling website, YES samples help- but it's all in when and how.
My partner and I are selling, we do a few things- this is at farmers markets often with SLOW traffic.
1- We always stand up and greet anyone who walks by.
2- We put it in their hands while saying "Smell this- handmade veggan soap- don't worry, you can't get it dirty- it's SOAP"
3- We walk away so they have to come to the table to put it down. There we encourage them to smell others while we tell them about the features/benefits of OUR soap.
4- If that interaction does not end with a sale, before they bolt we say " Well, before you go, Let me give you a free sample- What was your favorite smell on the table?" They always stop and smell ALL of them at that point. Once they pick a "favorite" we give them a sample of that with the tagline that "You should use it to wash your hands for 3 days, and when you notice the difference, we are here every (whatever) day- let us know what you thought good or bad so we can improve our product!" We keep our samples in a big sealed bin under the table, with little plastic bags, and when we put it in we mention "So your pocket doesn't get soapy."
We always make friends, MANY of those come back and tell us how they liked it, and many purchase when they come back. YES we work for the sale.
BUT handing out samples to everyone stopped pretty quick.... and we had several people at farmer's markets eat the samples. So, we make sure we say SOAP like 10 times.
Also, we always make small (Like 1/4th a normal bar) size ones up and go around to all the other vendors at a new market, and we ask: "Do you like fruity smells? Flowery Smells? Manly Smells? or NO Smells?" Depending on the answer, we give them a 1/4 bar, tell them about our vendor discounts, mention where we are, and get info about what THEY sell, so we can inform guests of other options.
If we see a new vendor who has samples of THEIR products, we always offer to take a small basket of them and put them at our tent, and tell our regulars about the new vendor too.
Ok... so I got off on a tangent about selling.... but I think it's related in terms of sampling and HOW/WHEN to offer a sample.
One time show, especially if you don;t have a good website etc.... don't bother TOO much.