No, it's not a common phrase at all. In normal English usage, it seems rather strange and not a typical expression you would hear in everyday conversation or see in general writing.
She can gain different perspectives. Strangers come from various backgrounds, and their stories can open her eyes to new cultures, ways of thinking, and life experiences.
It's not clear what 'flashing' means in this context exactly. If 'flashing' is used in an inappropriate sense, it's a very abnormal and unacceptable behavior. But if it means something like quickly showing or sharing stories with strangers in a non - improper way, it could imply that your wife likes to share stories with strangers in an enthusiastic or impulsive manner.
No. Such content is vulgar and inappropriate for public sharing. It violates moral and ethical norms and may also be against the rules of many platforms.
One story could be about a wife who met a stranger on a train journey. The stranger was an old lady who shared her life story filled with travels and adventures. The wife was inspired by the old lady's tales and it made her think about her own life in a new way.
It's relatively normal. People have diverse interests, and sex stories might be something she finds fascinating, perhaps because they offer insights into different cultural attitudes towards sex or just a form of entertainment within the privacy of her thoughts. However, it's important to ensure that her interest is within healthy and consensual boundaries.