Modding Weapons for Sale

I was very interested to read the following in the thread 'Guide to help Determine The Value of Weapons and Items':
Mainly because I think I've frequently been advised the exact opposite. I just wanted to check, whether this means (and whether people agree) that if you have a nice item with an undesirable mod (or no mod in one slot) and you replace that mod with a desirable one that the amount you could sell the item for wouldn't change at all. I would have thought the price would have increased, just not by as much as you could sell the mod for on its own.

Does anyone think it is ever a good idea to remod items you plan to sell?

Most people telling you that it does increase the value, well, suck
let me make a really simple example
a Req 11 15^50 chaos axe would normally get you something like 60K
If you now mod it with a sundering and fortitude, worth about 30K each
will the axe now be worth 120K? No, it will not.
You may sell it now for 70K or 80K, but not a penny more.
If you sell the mods seperatly, you'll make more money, the investment is not worth it(sundering sucks btw!!!!)

also, if buyers want to mod an item, they wont tell you, its easier for them to say they wont, and not pay for your expensive mods, they can mod them thereselfs.

In addition to that, not everyone wants 20/20 sundering or +30 fortitude. Some people might want Icy for interupts, Vampiric for more damage or Defense for more armor. Unless the buyer tells you want mods he wants and is willing to pay for that, i don't see why modding will increase the value of weapons, IMHO.

Thanks for your thoughts. I won't be modding items I'm going to sell again.