class Foo
{
private int _aThingId = 0;
// vs.
private int aThingId = 0;
...
...
}

2nd - I was arguing for the performance of casting. I could not recall an article to support my viewpoint that using ‘as’ style casts was prefereable for speed and also in order to remove those nasty ‘ice’s (invalid cast exceptions). ‘as’ is especially more performant when comparing vs ‘is’ compare THEN c style cast. Anyhow an article supporting the speed of ‘as’ vs c style casting is right here

class Foo
{
private void DoSomething( object foo )
{
Foo f = foo as Foo; //(null check later for invalid cast - no exception)
// vs. (potential invalid cast exception)
Foo f = (Foo)foo;
// or
Foo f;
if( f is Foo )
f = (Foo)foo;
}
...
...
}

3rd - using ‘this’ all over the place as an alternative to _ or simply in addition to _ in a class. I claim ‘never use this’ except in the ctor.

class Foo
{
private int val = int.MinValue;

/// this is OK by me and all others
public Foo( int val )
{
this.val = val;
}

/// this is NOT OK by me and many others
public void DoSomething()
{
if( int.MinValue == this.val )
{
//Do something useful
}
}
...
...
}

“3.2.32. Rule 3@505: Only use the this. construction to avoid a name clash
Do not use the this. construction to dereference members. The use of this is only allowed as a reference to
the current class instance or to prevent name clashing between method parameters and class fields.”