This is because when experts are asked about this problem, most are unwilling to admit it if they are viral killers, but most are also unwilling to deny that they have the "ability" to defeat all challengers. They will only hint darkly and say "what I've heard.
因為此中高手在被詢及有關問題的時候，多半既不肯承認是下毒兇手，又不肯否認自己足以攪翻武林的「功力」，只有含糊曖昧地描繪江湖傳聞了。