For months on end this has been a huge problem I've seen ppl complain about. No one wants to be thrown into 10000000rp or nonsense matches, right?
By doing this you will only get put into Rockstar Created and Verified matches (and friends created content if you pick that as your option)
We'll here is how you block them....
Xbox Home > Privacy > Change Settings > Customize
Scroll down to Content tab
Click on Member Content
Choose either "Blocked" or "Friends Only" ( I chose friends only)
Hit Back > Save And Exit
The game will ask you to log out. Do so.
Log back in and you're good to go.
You'll never see any of those crappy deathmatches again.
When you log into GTA online it will give you an alert that user content has been blocked. Hit ok and sign in. Best thing since sliced bread
edit: Known issues and work-arounds:
1. Crew Tattoo/Clothing Logo's Dissapear - no fix for this.
2. Get stuck in loading animation going into Garage/Apt. if cars inside have Crew Logo's on them - simply disable blocked content, reload game, remove crew logo's from cars. enable block content again, reload game. should work now.
3. Cannot create playlists (Vital for Heads Up Crew vs Crew TDM) - have a friend create the playlist and send you an invite, then you can join, or disable blocked content. (edit: you can edit your existing playlists)
4. Cannot Alter Your Custom Created Jobs. - disable blocked content. re-enable when done.
5. Cannot join Custom map you want to play - add creator as friend.
6. Cannot Access in-game crew menu from the pause menu - use rockstar social club website.
and the obvious solution to any of this is to just go home, disable, then re-enable when needed. it takes no longer than 2 minutes to change and be back into the game.