Promoting anything is an art form. It does not necessarily depend on the product being sold. It depends completely on the skill of the person who is promoting it. One can promote almost anything under the sun. One can promote whatever one wants.
There are different kinds of promotional products which are possible. One is the branded promotional products. And, there could be non branded products as well here. One could think of beautiful promotional badges through which one can promote these products.

These days, almost every product, branded or not, gets sold with some or the other promotional items only. People have become very value conscious and a lot more demanding these days. Hence, it has become imperative for them to ask for a lot more value in whatever they are buying. Giving promotional products along with the branded ones is one way of handling the requirement of giving value.

One can give away T-Shirts. One can give away mugs. One can give away photo frames. There could be a million other items which can be sourced and given away like this for promotional purposes.

When one can get something additionally and for free, why would that person want and take anything less than that?