this.KindOfCodeQueryExpression returns KindOfCodeQueryExpression.KindOfCodeQueryExpression.Rule if this code query is a code rule. Notice that a IQueryExecutionSuccessResult object can be modified when calling a ExtensionMethodsQuery.ExtensionMethodsQuery.GetIssues overload that takes a suppressedMessage set. In such condition if all issues are suppressed this property can return false although it was returning true before calling GetIssues().

Reference

IQueryExecutionSuccessResult Interface
IQueryExecutionSuccessResult Members