I do necessarily  agree with all statements in Clean Code by Robert C. Martin. One of the sections I though is completely obsolete was a statement about disinformative names:

“A truly awful example of disinformative names would be the use of lower-case L or uppercase O as variable names, especially in combination. The problem, of course, is that they look almost entirely like the constants one and zero, respectively.”

The corresponding example he gives is the following:

int a = 1;
if (O == 1)
  a = 01;
else
  l = O1;

So far I though it is obvious not to write such code, however, I came across similar code these days.

for (int o = 0; o < args.NewItems.Count; o++)
{
 string s = args.NewItems[o].ToString();
 ...
}

What’s the problem here? The variable name o is used for a counter and initialized with 0. While this is already hard to read, o might indicate that we deal with an object here. So when having just a brief look over this code you might get the impression it iterates through a set of objects. This is further supported by the usage of the NewItems property here, as in .NET object references is quite commonly used to resolve e.g. a key/value pair within collections.

When using a counter variable without meaning one should use common names such as i or j that a commonly recognized as counter variables.

for (int i = 0; i < args.NewItems.Count; i++)
{
 string s = args.NewItems[i].ToString();
 ...
}

This is only a slight modification but already improves the readability of the code.