I think I found a few of these and passed over them by accident as trash. But they have +1 INT! Where can I find this item easily and consistently?
According to the Nukapedia article on Road Goggles, the Pillars of the Community cultists found in Charles View Amphitheater may spawn with these.
This information seems to have been edited out of the article for some reason, but previously it stated that:
Because they rotate their equipped clothing periodically, the goggles may not appear on any of them when first encountered. Killing a cultist and reloading the game may result in their clothing being rotated, giving a better chance to acquire the item.
I tested this myself. The first time I went to the amphitheater, there was a cultist with the goggles on. I tried pickpocketing him, but it wasn't visible in his inventory. So, I was forced to kill him. The other cultists got all indignant, and I had to kill them too. Now there are less cultists, and I have goggles. Win-win.
If you have a few ranks in Pickpocket, then you can steal equipped items, and won't be forced to murder everybody.
That being said, killing the cultists will not prevent you from completing any associated quests, if you haven't done so already. As it says on the Nukapedia page for Charles View Amphitheater:
If the player character does kill Brother Thomas and his followers, Thomas will respawn later (at least for the Emogene quest) and a persuasion option threatening him will have the Sole Survivor say they "killed the last guy running this scam".
I found this to be true when I returned during the mentioned quest. Of course I just killed him again and picked the lock. She didn't mind.
Now, in the Automatron DLC, you can easily find Road Goggles on Zoe's corpse where you find Ada. The Nukapedia article has been updated to reflect this.
This quest is not triggered until level 15.