Please excuse this serious reply...
The magazine's journos are reporting on the event and probably want to convey the sense of fun enjoyed by the participants, it's difficult to capture fun and laughter in a magazine photo but the fancy dress will certainly help. When they're doing a feature on a car then people will want to see the car and not have it obscured by silly props.
I think they've got it about right and I appreciate their efforts when I'm stood reading their mags in WH Smiths
let me rephrase your sentence...
When they're going to (doing) a show(feature on a car) then people will want to see the car and not have it obscured by silly props.
mmm, strange how that works, isn't it ??