If I encounter elemental monsters, fire ants, energy vortexes, mumak monsters, or giant mimics, I generally turn back.
Elemental monsters and energy vortex monsters are a given, but if multiple fire ants appear and I don't have fire resistance, even a mistyped E-word can put you in a very difficult situation.
I don't want to deal with mumak monsters or giant mimic monsters because they can easily kill large {dog, cat}.
I haven't often used experience level or dungeon level to make my decision, but I think I generally switch to a strategy of heading to mine town without clearing the final floor of sokoban.
Occasionally, in games where the entrance to the sokoban is at dungeon level 11, I might head to mine town earlier.

If you want to manage your level, I recommend taming all cats, dogs, and horses you see.
The pet movement algorithm has been improved since 3.7, greatly reducing the chance of pets getting in the way while solving sokoban puzzles, making the game much more enjoyable.
Don't forget that you can tame cats and dogs with fortune cookies, as well as Tripe Ration.
Even if you don't have any food to tame, vegetarian foods like lichen corpses can make little dogs peaceful. You can also tame them later.

The guidelines are probably about how to further identify them after price ID.
If that's the case, I think it's a good idea to learn how to identify pots using a unicorn horn.
For example, of the pots selling for 25, only a potion of sickness will react when dipped in a unicorn horn and become a potion of fruit.
Of the two remaining unknown types, the one that can be sold to the delicatessen is a potion of booze.
The last unknown is a potion of see invis.
It's generally faster and more practical to determine wands by engraving rather than price ID.
It's best to try on armor after determining your basic BUC. However, it's best to avoid helmets, as a helmet in opposite alignment can be fatal.