Null + Type checking with cast (bad) and with is operator (good)

bad.cs

//This is bad, don't do this:
if ((SubclassType)BaseClassInstance != null)
{
  //this will run, maybe, who knows?
}

betterbutstillbad.cs

//This is better, but still ugly...
try
{
  if ((SubclassType)BaseClassInstance != null)
  {
    //this will run, maybe, who knows?
  }
}
catch (InvalidCastException ex)
{
  //handle the error
}

good.cs

//Do this instead:
if (BaseClassInstance is SubclassType)
{
  //ah, much better...
}

goodbutreallyugly.cs

//Not sure which is uglier...
if(BaseClassInstance != null && BaseClassInstance.GetType() == typeof(SubclassType))
{
  //wow, that was a mouthful.
}