yeah, coming from a habitually sad person, it's hit or miss and in most cases there's no way to really gauge if you're going to make them feel worse. I can't speak for anyone else but personally, if I'm really sad in public, the only thing that a stranger could do/say that wouldn't be a risk of making me feel worse, is asking 'are you ok'. and so that's what I tend to do, if anything, when I see someone who looks really sad. just a thought