To find people suitable for a job in entertainment there is a step by step process similar to any other type of recruitment.
For example if the person already has worked in the costumes sector for 5 or more years (as they might were they to be working at www.70-fancydress.com) then they will have developed a certain confidence about their work. They know what types of providers to call and how to talk to them and get the best deal. So a little look at their c.v. will allow you to short list those types of applicant.
Alternatively if a particular type of personality appeals but they do not seem to have the experience of working in entertainment, then a question and answer session will show how well they might match up to the job. For example did they run parties and if so, for whom?
What type of providers did they deal with?
Were they involved in hiring fancy dress costumes for particular themed parties?
Did they organise gits and freebies as handouts at the end of the party?
What type of music did the set up?
Were there acts to organise and how closely did they need to work with the performers and look after them?
So at first it might seem on paper that the candidate is not right for the post, but at the interview you could form an entirely different opinion of them and it will be then be your task to see if what they were doing previously is actually a very good fit for the post you are seeking to fill.