In a bit more detail:
Besides the loot from your victims, you see and get some system-generated loot on every raid. With every raid you do, the amount of system-generated loot you see gets lower. Also, it may be a bit lower or higher for some bases than for others, but basically the reduction affects all bases you look at.
So if you did e.g. 10 raids in a row, you won’t see any decent loot anymore, except you view some player that has actually left a huge amount of actual (non fake/system-generated) gold unprotected in his treasure chamber (for example because that player lost internet connection, or forgot to start an upgrade after his raiding session). Though, currently basically everyone is raiding to get those new upgrades released some days ago, so actual real big loot is very rare at the moment.
Thus, you mostly depend on your luck and on the system-generated loot, which increases again (slowly) over time. So if you see no good loot, go offline and check some hours later.
I think many months ago, there was an exploit called the “1 gem trick”. This was, buying food (for at least 1 gem) completely reset the system-generated loot to default/maximum. However, this was fixed long ago. Now, the loot doesn’t get reset completely when you buy food, but only a little bit, and more if you buy a bigger amount of food.
Though, especially if you have a gold shield, it may not be worth it to spend like 60 gems to reset the loot. Rather wait for a while.
Now, here is the place
Not sure if long ago there was any other topic about this… probably, but just search the forums.