What is an example of SM gone wrong?

What are things that create issues with SM and anyone know of any examples happened and how to motigate then?

I understand the following can become issues:

• Comingling can creat tax issues
• Buying ineligible assets
• Selling in down market
• Over extending with margin and getting called
• Credit acore drop and HELOC called back at down market
• Bug proper value loss due to markets or otherwise
• Property in fire? Insurance pays very late I hear
• Variable rate mortgage and HELOC and rates going up and dividends not going up aince the two are not tied