The gifts offered at trade shows should serve a specific purpose and be in context of the subject of the exhibition stand. For instance, it sounds lame if a software company gives away plastic bottle at trade show floor. The freebies should primarily serve the purpose of engaging potential clients in conversation. The gifts should attract quality leads instead of unqualified leads that are vague.
Source: https://www.fountainheadint.nl/blog/top10tradeshowmistakes/