being told it often 来自薄冰英语语法

being told it often 来自薄冰英语语法
She rebuked herself for forgetting what she really knew quite well,having been told it often.
她常被告以此事,所以她责备自己忘记了她实以熟知的事.
如后句换成being told it often,会产生何种歧义呢?
书上的解释是：除了具有having been told it often的含义外,也可能具有“经常被告诉”的意思.
不过没看懂.