TLDR:

You can trust zaps to yourself, so you can use zaps for ranking dms or personal spam filtering.

You can’t necessarily trust zaps sent to other people, which makes things like ranking unreliable (top zap list, etc) nostr:note1xx2nmgayvqkru0yf5m3w6p69xzn7f5vtx7jzzxh27qtp7zkjw6msgk0m6d