I saved up all my Golden Keys until I hit 50 and used them all at once hoping for some really nice items. I ended up with a bunch of vendor trash...most items were either downgrades or marginal side-grades with downsides that I couldn't live with. Twice in a row I got two pairs of useless sniper rifles...then twice I got two pairs of E-Tech SMG's with no elemental or special effects that I will probably never use.
I've used six Golden Keys in all, all at Level 50 with the Vault Hunter's Relic equipped, and no luck. What has been your experience at 50 with the Golden Chest in Sanctuary? Back to farming the final boss!