On reading this guide about mobile traffic ( http://www.imgrind.com/marketing-gui...emarketing.pdf), the author emphasizes that wifi traffic is shit and should he avoided, thus targeting carrier traffic only. Why is wifi traffic bad? It seems counterintuitive to me, as wifi networks are typically better than 3G in terms of bandwidth and quality of service.
It depends what type of offer your running, from my experience wifi is fine for CPI offers but not for offers that require carrier billing.
Depends on targets sometimes.. if its game apps.. wifi will mean high percentage of kids playing at home and error clicks (game app developers have a knack of sticking a banner near a well used button or menu)..
If its a mobile content offer.. carrier traffic is often easier to convert with one or two click flows... wifi users will need to get a text to subscribe..
There will be more reasons. . But there's two obvious ones
It is bad generally for pin submit / 1-click flow offers.
For app installs it's better than carrier since download speeds are generally faster.
Its not shit. Its shit because his network doesnt have many wifi convertinv offers so he wont profit off you when you work with the top cpa network in the world 
^ nicely put!
Lol I'll take all the wifi traffic I can get. Give it me! Even for pin submit offers wifi is good.
I've been running mobile for 3 years full time now, and I've always used wifi traffic...you can monetize it with a tonne of offers.
Miss information at its finest.
I've also read some guides in this forum that said that... That quality gets better with non-wifi traffic.
They also recommended blocking app traffic for testing, but I really cannot get why. Any clues? Is that because apps don't get fresh new users daily?
^^App traffic is usually lower quality. Due to spammy/fraud apps. As well as fingers tapping on ads by mistake whilst in games.
Once again do your own testing. App traffic all can be bad, it can be good too. It depends on the network, and your campaign. I've found plenty of gem app placements. Just make a separate campaign for apps, lower your bids. Don't block apps out from square one.
Make 4 campaigns:
APP + WIFI
APP + 3G
Sites + Wifi
Sites + 3G