What constitutes excessive appealing?

There was an appeal. A very good appeal. And the umpire finally decided in favor of the bowler. The Cricinfo commentary describes it thus

That is crucial. If any man was likely to dig in to the close, it was Nash, the mini-Chanderpaul of the middle-order. So ... four wickets now, and the best part of two hours to claim them. Game on!
96.3	Swann to Nash, OUT, that's the breakthrough, and that looked especially tight! There was no discernible spin, and struck the middle of the pad well before the bat was involved. Umpire Harper thinks long and hard, but gets his decision right in the end

What is not mentioned is the prolonged and sustained nature of the appeal. I counted atleast four "Howzats" from Graeme Swann before the decision was made. And it is very likely I missed a couple more.

There have been previous instances when similar obvious decisions have not gone in favor of the bowler because, to quote the commentators, the appeal was not strong enough.

Per the ICC

Excessive appealing -Excessive shall mean repeated appealing when the bowler/fielder knows the batsman is not out with the intention of placing the umpire under pressure. It is not intended to prevent loud or enthusiastic appealing. However, the practice of celebrating a dismissal before the decision has been given may also constitute excessive appealing.

Now, if the bowler/fielder knows the batsman is not out, why have the umpire?

And if the bowler/fielder dont know, how can the instance listed below be anything more than "loud and enthusiastic appealing" ?

Mushfiqur, the wicketkeeper, had appealed confidently believing Tillakaratne Dilshan had edged the ball off the bowling of Mehrab Hossain jnr. He ran towards the umpire while appealing before stopping about six metres in front of the batsman. Ashraful, the captain, too joined the appeal from his position at midwicket and stood near the pitch after the appeal was rejected.

And if excessive appealing is really all that, can someone explain this

20.5	Muralitharan to RG Sharma, OUT, another excellent delivery from Murali, tempting the batsman forward and he plays down the wrong line as the ball bounces away from him, taking an edge. Sangakkara pouches and is almost celebrating before the decision comes. No third umpire is called for and he's on his way, but could be in trouble later as he stood there for a while, unhappy with the call
	RG Sharma c Sangakkara b Muralitharan 0 (1m 2b 0x4 0x6) SR: 0.00

Rohit Sharma was fined 10% of his match fee for dissent after being incorrectly judged caught behind for 0 off Muttiah Muralitharan at the Gabba. Sharma was the second India batsman to remain camped to the crease following his dismissal over the past six weeks, but his punishment was stronger than Yuvraj Singh's following an in-depth pre-series discussion on behaviour by Jeff Crowe, the match referee.

PS:-

And after that excitement, Flintoff has left the field.
104.6	Anderson to Taylor, no run, massive appeal though who knows what for! Cracking delivery from Anderson, zipping off the seam and over the top of the stumps. It could have been an appeal for a catch or lbw, but replays show the noise was shirt. Another good decision from Harper

Alan Hurst, I will be watching!