I wasn't obsessed with them, but I liked them a lot. But then I love all that stuff a lot, I was obsessed with mythology as a kid.
While we think of many classical mythological mermaids as not exactly friendly, it depends on if you think of sirens or nereids. Nereids are the little mermaid style, and were generally good(though also not always sexy, as some versions had them with full scales and with fish mouths

). Sirens are the "evil mermaid" that lured sailors to their death, but were actually more like harpies that became conflated with mermaids over time.