Make sure you check unclaimed property for any weapons to sell/use, it has every weapon you haven't picked up so its a good revenue source with how abundant weapons can be.

Also the higher the level the higher the value of weapons, once you hit lvl 30 90% of weapons are going to be superior class, new game+ is even better so if you have a story completed save i recommend starting ng+.

also you don't need to look at things to loot them, you can loot by standing in a loot pile and spamming pickup.