Thanks for the feedback. I am glad to know that there are some mostly-shared limits even among degenerates like us.  

I hadn't seen the term "shark week" before, so I need to remember that. I have always told GFs, SBs, and escorts that there is no need to cancel an appointment or avoid sex with me because "Aunt Flo" is visiting unexpectedly. However, I like "shark week" more; I plan to use this term with my less squeamish friends. It sort of brings to mind Picasso paintings with toothed vaginas.

I just read about someone enjoying tampon-still-inside sex with an escort. He apparently asked her for it. I have never had it offered, nor does it seem interesting.  

As to why it would be unsafe, why would menstruation make it more unsafe than normal non-menstrual sex if covered? If bare, wouldn't any BBFS be unsafe without trust and exchange of test results regardless of the time of the month?