Like any other industry, the quality of suppliers varies from the good through the bad to the plain ugly. The cream of the professional operators will supply high quality, attractive items that are well maintained, have been cleaned prior to your event and are staffed by uniformed attendants. This last point by the way is actually a health and safety requirement, if the staff from your supplier are not in uniform they are ignoring health and safety regulations, which ponders the question what else are they ignoring?
As a minimum any competent funfair operator will supply the following items as part of his safety documentation;
Event risk assessment
Event Fire Assessment
Individual attraction risk assessment
Individual attraction fire assessment
Event method statement
Individual attraction method statement
Individual attraction safety and testing certificates
Public liability insurance documents
Written health and safety policy
Most of these items are actually legal requirements for service providers, so if any of them are missing, ask for them, if they are still not supplied then find another operator, in...