Why is this an issue?

When you call Any(), it clearly communicates the code’s intention, which is to check if the collection is empty. Using Count() == 0 for this purpose is less direct and makes the code slightly more complex. However, there are some cases where special attention should be paid:

• if the collection is an EntityFramework or other ORM query, calling Count() will cause executing a potentially massive SQL query and could put a large overhead on the application database. Calling Any() will also connect to the database, but will generate much more efficient SQL.
• if the collection is part of a LINQ query that contains Select() statements that create objects, a large amount of memory could be unnecessarily allocated. Calling Any() will be much more efficient because it will execute fewer iterations of the enumerable.

private static bool HasContent(IEnumerable<string> strings)
{
  return strings.Count() > 0;  // Noncompliant
}

private static bool HasContent2(IEnumerable<string> strings)
{
  return strings.Count() >= 1;  // Noncompliant
}

private static bool IsEmpty(IEnumerable<string> strings)
{
  return strings.Count() == 0;  // Noncompliant
}

Prefer using Any() to test for emptiness over Count().

private static bool HasContent(IEnumerable<string> strings)
{
  return strings.Any();
}

private static bool HasContent2(IEnumerable<string> strings)
{
  return strings.Any();
}

private static bool IsEmpty(IEnumerable<string> strings)
{
  return !strings.Any();
}