Improper venting for toilet pipe?

[HouseFix]

Plumber vented the toilet pipe for 3 bathrooms in 3 different manners. I think method 3 is the proper way and method 1 is improper / illegal? Not sure about method 2. Can someone please confirm?

If method 1 or 2 is improper, whats the risk / problem it will cause (plumbing wise) if its not corrected?

Note: All pictures are taken looking up towards the ceiling, the smaller 2 inch pipe is the vent.

Method 1:


Method 2:


Method 3:

 

[Stuff]

What does the inspector say? The horizontal sections are not code as a vent unless it is a wet vent (washed by lavatory).

A popular picture:

 

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[HouseFix]

@Stuff - Thanks for the chart, very helpful. When you say "The horizontal sections are not code as a vent unless... wet" are you referring to the horizontal section shown in Method 3, where the 2 inch pipe is connected to mid-pipe?

The 2 inch pipes are all dry vents, which seems like based on the chart, neither method 1 or method 2 is correctly piped?

Inspector didn't show up for the inspection (very common in my area), which means the plumber gets to self-certify the job was done to code.

 

[Stuff]

Even #3 is not good. Issue is that if the line backs up that vent will fill up with sludge. Since horizontal it needs water from a fixture such as the bathroom sink to wash it out. What will happen is that all three will work fine for years but slowly clog the vents. You may not actually need vents for these three but that is whole other argument.