You might think it's an innocent remark, made at random in the stands: "why does my skater's coach let the kids just stand around and talk?" "I'm so mad at my skater's coach, she was late for the lesson again!" "My skater didn't do well at competition because I think coach pushed him too hard." "That coach only pays attention to her own skaters in class."
In reality, you actually love the coach, you think the skater's doing well, and you're not really unhappy. You're just sitting in the stands, bored, or frustrated, or listening to the other parents talk, and you feel like you have to say something. The conversation veers into the negative and you don't want to sound like Polyanna, so you pick something negative almost at random.
But this is how bad reputations get made.
We know, intellectually, that gossip is bad. But the definition is very vague, and everyone claims that they don't indulge in it. Saying "coach is late" when in fact the coach is late, isn't gossip, right? It's a simple statement of fact. But your statement that the coach is late will turn into "I heard that she was late again" which will turn into "that coach is never on time."
You might know perfectly well that the reason your coach was late is because her car is in the shop and she's relying on public transportation, which she isn't used to. Or she has a sick child or spouse. But the remark just slips out, and next thing you know, that coach has a reputation for being late, even if it was just once or twice.
Everyone gets frustrated with their coach. But there are exactly two people to talk to about it-- the coach, or if the situation is out of hand, the skating director. And there is one place you should NEVER talk about it and that's in the lobby or the stands. Serious conversations with the coach belong on the phone, in a remote coffee shop, or even Google chat. (Don't do it by email; email has a way of getting out of hand. If you start an email discussion and it goes more than 3 times back and forth without resolution, or starts getting negative, pick up the phone.)
Fighting with the coach in the lobby, indulging in off-hand (or worse, calculated) criticism, or passing on overheard remarks are reputation-wreckers, for both you and the coach, with your child as the collateral damage.