Hi,
I think I may have solved my bra strap exposure problem myself!
That is, unless you are quite brazen, like wearing a black bra under a painted-on sheer white top, or like revealing your straps with a racer back top, or let them slip down, then in fact, nobody notices or seems to care very much.
I decided to go shopping wearing a sexy pink plunge bra under a loose red tee shirt, with a fleece on top. With my bra & top colours matching, who could possibly see anything? Checking in the mirror, nothing seemed to show under my shirt. The bra padding also hid my nipples, which for me can be quite obvious with no bra.
In the mall, the sun came out and I confidently removed my fleece. I went into several shops and queued in a coffee shop with women right behind me (who would quickly notice a bra).
Then to my horror, I caught my reflection in a shop window in full sunlight. My bra had buckles at the top of my shoulders, halfway down my back and also where the straps join my back band.
All these buckles, plus my bra band fastening were clearly visible! That's seven bra-related bumps across my back.
But nobody paid any attention. No bra police arrived.
At least I didn't have the problem of the falling bra strap. As a rule of thumb, if you can pull your strap up to your ear, it is too loose. Once you get them tight enough though, regular bra wearing produces permanent grooves in your shoulders, into which your straps snugly locate!
So maybe the rules are:
Wear a flesh coloured bra, or one which matches your top colour.
Don't wear tight or racer-back tops.
Make sure your nipples don't protrude, maybe by using bra petals.
Choose bras which don't have buckles across the middle of your back.
Tighten your bra straps into your shoulder grooves.
