C# - Bad Practices

Question

What are some of the bad practices you have seen in C# or .NET in general, there are plenty of posts on "good" practices, but I have not seen one on bad practices.

If this is OT then please delete.

Answer 1

Not using LINQ where appropriate.

Answer 2

a simple bad practice that comes to mind is to concat strings with +

string bigString = smallstring1 + smallstring2 + smallstring3 + ...

instead of using StringBuilder

Answer 3

if (boolCondition == true)
{
   // do x
}
else
{
   // do  y
}

Instead of:

if (boolCondition)
{
   // do x
}
else
{
   // do  y
}

Answer 4

Should all be listed here.

Answer 5

string s = "H"+"e"+"l"+"l"+"o"+" "+"w"+"o"+"r"+"l"+"d";