Unity EditorWindow to show how many components there is inside a gameObject hierarchy (put the script inside an "Editor" folder)

ComponentsViewer.cs

using UnityEngine;
using UnityEditor;
using System.Collections;
using System.Collections.Generic;


public class ComponentsViewer : EditorWindow
{
	[MenuItem("Window/Help/GameObject/Components Viewer")]
	private static void Init()
	{
		ComponentsViewer _window = GetWindow<ComponentsViewer>();

		_window.title = "CViewer";
		_window.Show();

	}// Init()

	private const string gameObjectTypeName = "GameObject";

	private const string transformTypeName = "Transform";

	private Transform root;

	private bool includeInactive = false;

	private bool removeGameObjectTransform = true;

	private bool removeNamespace = true;

	private Dictionary<string, List<Component>> components = new Dictionary<string, List<Component>>();
	private List<string> keys = new List<string>();
	private int nbComps = 0;

	private Vector2 scrollHeight = Vector2.zero;

	private void OnGUI()
	{
		// root
		root = (Transform)EditorGUILayout.ObjectField("Root", root, typeof(Transform));

		if(root == null)
		{
			EditorGUILayout.HelpBox("No root means it will scan ALL the current scene !", MessageType.Warning, true);
		}

		// inactive ?
		includeInactive = EditorGUILayout.Toggle("Include inactive", includeInactive);

		// remove gameobject and transform inside list
		removeGameObjectTransform = EditorGUILayout.Toggle("Don't list gameobject and transform", removeGameObjectTransform);

		// remove namespace
		removeNamespace = EditorGUILayout.Toggle("Remove namespace", removeNamespace);

		if(GUILayout.Button("Refresh Components List"))
		{
			FindComponents(root, includeInactive, removeGameObjectTransform, removeNamespace);

			return;
		}

		// nb comps
		EditorGUILayout.LabelField("Components : " + nbComps.ToString());

		scrollHeight = EditorGUILayout.BeginScrollView(scrollHeight);

		for(int i = 0; i < keys.Count; i++)
		{
			// key
			EditorGUILayout.LabelField(" - " + keys[i] + " : " + components[keys[i]].Count.ToString());
		}

		EditorGUILayout.EndScrollView();

	}// OnGUI()

	private void FindComponents(Transform root, bool includeInactive, bool removeGameObjectTransform, bool removeNamespace)
	{
		Component[] comps;

		if(root != null)
		{
			comps = (Component[])root.GetComponentsInChildren<Component>(includeInactive);
		}
		else
		{
			comps = (Component[])GameObject.FindObjectsOfType<Component>();
		}

		// clear list
		components.Clear();

		if(removeGameObjectTransform)
		{
			for(int i = 0; i < comps.Length; i++)
			{
				if(comps[i] != null)
				{
					string type = GetComponentName(comps[i], removeNamespace);

					// NOT transform or gameobject
					if(type != transformTypeName && type != gameObjectTypeName)
					{
						AddComponent(type, comps[i]);
					}
				}
			}
		}
		else
		{
			for(int i = 0; i < comps.Length; i++)
			{
				if(comps[i] != null)
				{
					string type = GetComponentName(comps[i], removeNamespace);

					AddComponent(type, comps[i]);
				}
			}
		}

		keys.Clear();

		keys.AddRange(components.Keys);

	}// FindComponents()

	private string GetComponentName(Component comp, bool removeNamespace)
	{
		string compName = string.Empty;

		if(comp != null)
		{
			compName = comp.GetType().ToString();

			if(removeNamespace)
			{
				int _i_nameSpace = compName.LastIndexOf('.');

				// namespace >> remove
				if(_i_nameSpace >= 0)
				{
					compName = compName.Substring(_i_nameSpace + 1);
				}
			}
		}

		return compName;

	}// GetComponentName()

	private void AddComponent(string key, Component comp)
	{
		// key
		if(!components.ContainsKey(key))
		{
			components.Add(key, new List<Component>(32));
		}

		// add entry
		components[key].Add(comp);

		nbComps++;

	}// AddComponent()

}// ComponentsViewer : EditorWindow