There is no misconception about BDBS. Those of you who havent experienced any issues with this medium-- excellent.
Other people have. Just because you haven't doesn't nullify all the incidences of those who have.
The consensus on this forum is that it poses no issues.
Go outside this forum onto fish forums, ask experts in bottom-dwellers (not just corydoras, actually) what they recommend. It will not be BDBS.
The problem is whiskers in this case, yes. The issues of bacterial growth/fungus are secondary to the sharp materials rubbing on whiskers and bottoms of fish. Tissues and whiskers get eroded, secondary bacterial infections get a hold where if the proper medium ( a substrate with rounded, as opposed the angular edges) was used the bacteria would not be able to proliferate.
I'm pretty sure BDBS and PFS (what the heck is "regular sand") are both harder than corydoras so what difference does it make if one is harder than the other? I hear about BDBS being an issue with corydoras so why not khuli loaches, bristlenose plecos or dozen of other species. Why is it the whiskers? wouldn't it cut their bellies if it's an issue? Why doesn't it bother ottos, are they that tough?
I understand anecdotal evidence but how can loads of hobbyist raise these fish for years on this medium if it's an issue? I understand that successfully keeping corydoras on BDBS is not proof that it's safe, but having issues when it's in your tank is no proof that it's not.
Regular sand is sand with rounded edges- not angular. If you look at the care of bottom-dwellers on reputable sites it is universal to put these fish on substrate that is composed of sand particles that are rounded.
Take the Kuhli loach, since it was brought up. On Simply Fish it states that: "
"Use a soft, sandy substrate since this species likes to dig and tends to spend some of its time completely buried. When coarser gravel is used it may become stressed or damage itself, and feeding behaviour can be inhibited."
"Depending on locality the substrate may be composed of peat, mud or sand with the fish typically abundant in piles of leaf litter."
This is one example.