Zero spread, advantages and disadvantages


I search about zero spread in some foruns and I noticed a lot of people saying:

“I’m counter because, A, B and C reasons!”
“I’m favor because X, Y and Z reasons!”
“I like!”
“I dislike!”
“It’s good!”
“It’s bad!”

So, I think that this approach is incorrect. I think that correct approach about zero spread (like all in financial market) is:
Which are the advantages? And which are the disadvantages? Where, when and how is appropriate to use the zero spread?[/B]


Thank a lot!