I've been having a terrific time learning the ropes of AM with pops on US ZeroPark traffic. Up to this point I've not done any spying and just been coming up with my own angles / landing pages. I'm currently doing sweeps (win iphone 6, enter to win 5k, etc) on desktop. The best performing LP I've been able to come up with so far has topped out at 7% CTR and is consistently at 4 - 5 %. The best CR I've been been able to achieve though is 1%. I think it's high time for me to start spying and getting more inspiration to work from!
Does anyone know how to spy on desktop pops on ZeroPark ? On a side note, if running desktop pops on US ZeroPark is a bad idea for sweeps please also tell me that 
Well I read somewhere that the biggest vertical on zeropark are sweeps so you should be fine running sweeps there. I will leave the answer to spying for someone else as I'm not in a position to give you an experienced answer on that 
I would recommend getting on a proxy like HideMyAss and browsing around on movie streaming websites. Pops galore.
It may be a bit harder finding sweeps as many pops you'll come across will be mackeeper, gambling, make money etc.
Remember to turn Adblock off :P
Thanks for the help! I took your advice and managed to find some good LPs to get inspiration from. Looking forward to trying some of these new (to me) angles out!
You asked about pop traffic, but this is what I did for redirects. It might help in some way.
1) Make a list of major websites in your targeted niche. For example, if you're doing games then sites like armorgames,com would collect a ton of direct navigation traffic.
2) Create a bunch of misspellings for that domain. With our armorgames.com example, you'd want to try things like amorgames.com, armorrgames.com, etc. Add duplicate letters, remove letters, add letters next to one another on the keyboard, etc.
3) Go to these sites. When you visit, watch the URL paths. You'll find a lot that redirect through Zeropark, DNTX, etc. These are redirects you could be buying.
4) Refresh to see the offers that are represented by different levels of the bidding structure.
Enjoy!