The loot scale mystery continues to plague us all for many years in the past and likely until the end of the game. There is no real known answer unless the actual logic is released which I would guess will never happen. As a result, everything that is heard is general speculation, many of these ideas can be partially experienced, some are debatable, some are just purely wild ideas.
The few things that can be confirmed...
- If you farm with alts, although there is an increase of drop volume, that's due to the math that the chances may be increased simply because each alt can receive a potential drop. This is similar to playing with 3 players, the total drops the 3 players would get would be more than if just one player was solo.
- On the other spectrum of that, and as much as this is well known, I have learned that some players don't realize this, that by having a Hero or Henchie in the radar distance of the kill, items can be assigned to those heroes/henchies and will never be seen, as a result, decreasing the drop rate.
- Favor does increase the drop rate of gold items (keep in mind that other loot scale logic may come into play), but in general, the number of gold drops from kills (not from chest) are increased during Favor.
Other suggestions that I have heard, some I believe are plausible, some I don't. Again, I am NOT saying these are true, just sharing the theories I have heard over the years...you can choose which ones you want to test or believe or even laugh at as I do with a few 
- The more farms in a row at the same location can decrease drop rates, as a result some switch their farms often, maybe in a rotation format.
- AOE's or any form killing groups at one time can decrease the drop rate.
- Taking different paths while heading to farm spot can help the drop rate.
- Using different weapons or armor piece for each farm run can help the drop rate.
- Using different tonics or minis can help the drop rate.
- Adding different dyes to armor between so many farms can help the drop rate.
- Longer breaks from a particular farm location (weeks, months, etc) can help drop rate
- Each Campaign and each location may have different drop rate logic
- Logging out between farms can help the drop rate.
- Switching chars between farms can help the drop rate
I am sure there are more I didn't think of and likely more that will come to light on this post.
As always, wishing good luck to everyone, may your good drops be plentiful!
Chevy
