Tell a seller everything thats wrong with their house or no?

[Ralph Stowe]

I went to a local gathering for a guru who is pretty successful and has developed a following.  His strategy when negotiating with a seller is to justify his low asking price by pointing out "The house needs this and the house needs that, and that could all add up so that's why I can't go much higher on my asking price..." 

Now I went to ANOTHER guru who is also successful and has a pretty big following in town, but HE says, "Don't tell a seller everything that's wrong with their house. It upsets them. You're insulting their most prized belonging. Let them give YOU a number first and work from that. If they absolutely won't give you a number, work it backwards from,  "Well I need to make __% on this, plus I have X costs involving ____, so by my calculations, I'm somewhere in the neighborhood of $____.  and don't deviate from that too much. If you go up $20k or more, the seller thinks, "This person just tried to rip me off for $20k or more!" and won't want to do business with you." 

In your experience, is it more successful to point out all the houses flaws to justify a lower offer, or simply sympathize with the sellers situation and leave the house flaws out of it?