how do you determine if you have a hacked ditto?
Good for people to know
You could do some simple hackchecks to see if it has any details that's not possible to have on a Ditto (yet, anyway). Like a Met level that's too low/high, met in the wrong area, a suspicious OT/TID. But even if a Ditto does pass all these, that doesn't mean it's not hacked. In the case of 6IV Dittos, the rate of hacked ones and legitimate ones are incredibly high in the favor of hacks, since some websites mass-distribute hacked 6IV Dittos to those who don't want to SOS-chain for 4+IV ones. I wouldn't trust a 6IV Ditto to not be hacked, unless I SOS-chained it myself, or knew for certain that someone very trustworthy did.
If I got something like a 4 (or less) IV Ditto from GTS or WT or such, I wouldn't necessarily think it's hacked if it pass the simple hackchecks, since if it was hacked by someone, they'd make it 6IV, 5IV (0 Speed) or such. But I wouldn't use it personally, since I already have good enough 4IV Dittos.