My daughter lived there for a while and we visited/stayed on many occasions. She isn’t military but supported the MOD and Gibraltar Govt - aviation. I have to say we didn’t perceive any animosity or resentment from locals or Spanish either side of the border. Most residents and the massive daily influx of workers seemed too busy getting on with their fairly manic lives. At the risk of causing offence, the only group I thought were remote & standoffish was the local jewish population.