Being a marshall is a thankless task anyway. I did a stint at a SWEFTA GP at Dartmoor some years back, and I was on a kneeling lane for most of the time. A well-known competitor who I won't name adopted a position that looked in breach of the rules, and in a friendly way I asked him to check his position before taking the shot.
Being a relatively unknown on the national circuit, who the heck was I, this upstart, daring to challenge someone who was far more famous than I was? The verbal abuse is unrepeatable.
I don't need that grief so that is the last time I marshalled a kneeling lane. Since then at the East Devon GPs I've been the drinks monitor, at least that gets some appreciation.