>looking on GTS for pokemans I need for breeding because I can't be assed to go catch a fuckin bagon
>level 1 bagon up for trade
>guy wants treecko
So you highlight all six symbols on some random ass Treecko, regardless of how many IVs it actually has, and then send it hoping the receiver trusts your use of the symbols and doesn't actually check its IVs.
my point is, if I got a 0IV ditto in a trade, it would be noticable that its all 0 IVs when I check it. Plus, sometimes you need a couple of non-31 IVs and zero is usually a good option, like in the case of a physical attacker or a Hidden Power-reliant 'mon.
Just catching ditto en masse is a better, more heart-breaking tactic. Making sure they have no perfect or 30 IVs of course