using System;

using System.Linq;

using System.Xml.Linq;

using System.Xml.XPath;

public class Program

{

    public static void Main()

    {

        var xml =

            @"<specs>

                <spec name='fald' value='100'>

                  <name foo='' bar='askdh'></name>

                  <value foo=''></value>

                </spec>

                <spec value='100'>

                  <name></name>

                  <value></value>

                </spec>

              </specs>";

        var doc = XElement.Parse(xml);

        var childrenToDelete = doc.XPathSelectElements("//spec/*")

            .Where(elem => string.IsNullOrEmpty(elem.Value)

                   && (!elem.HasAttributes

                   || elem.Attributes().All(attr => string.IsNullOrEmpty(attr.Value))))

            .ToList();

        foreach (var child in childrenToDelete)

        {

            child.Remove();

        }

        Console.WriteLine();

        Console.WriteLine("Result:");

        Console.WriteLine(doc.ToString());

    }

}