When companies hire models to represent products, what they're looking for is someone who's casual and natural while also being friendly, outgoing and attractive. This is doubly important at trade shows. Observing trade shows can tell you a lot about the right and wrong ways to use models for your business, because the model is "on the spot" for the entire show.
Trade show models, working in person, have to be outgoing, and be "people" people. They have to like interacting with people and they have to convince the person who's hesitantly approaching them with a primeval fear of rejection that they are approachable, that they are interested in what the trade show is about, and that they can competently answer any questions the trade show attendee has. To do this, it's important to dress appropriately for the trade show. If your trade show has people in suits, your model needs to be dressed in business attire. If your trade show has attendees in jeans and tee shirts, a model needs to dress in khakis and polos. Having a model dress in skimpy outfits at a show where that's not the expected attire will result in a "10 foot exclusion zone", where the attendees won't know how to interact with her, and will be afraid of rejection...and if the people aren't coming close to the model, the model isn't doing their client any good at all.
Ultimately, the purpose of a model at a trade show is to help a company promote a product. People looking at getting into modeling need to keep that in mind - they have to do more than be just a pretty face, they have to engage customers and act as the first line of sales agents.