Reverse-engineer this question. What makes a horrible, unsmokeable pipe? Let's build a pipe and drill the stem at 1/16" all the way through. Not only would you never be able to get a pipecleaner (maybe a paperclip) through, but the thing would gurgle incessantly, any tiny bit of moisture would totally occlude the airway. And you'd have to suck and suck and suck just to keep the thing barely burning. That would be .... a bad pipe. These things exist, I have previously posted pictures and exposition on this.
If you think the miniscule andvery rough slot on the right is going to offer the same smoking experience as the slot on the left which is deep, smooth, and actually big enough to put a pipe cleaner in, you are weird. Never mind the discomfort of all the sharp edges on the stem on the right.
So I mean, my hypothetical example of a pipe built intentionally badly is probably not that hypothetical in the first place, and even if it is, there's lots of ways pipes can be poor - bad tasting bowl coatings or dip stain in the chamber makes for a long, arduous break in. Uncomfortable stems are easy to find. Pipes where the drilling is pretty badly lined up make it tough to pass a cleaner through if you need, and certainly don't help with the smoking.
Pipes that are carefully made, reasonably carefully, smoke better than pipes that are not. Luckily, lots of pipes are reasonably carefully made - most Savinellis are entirely adequate in my experience, just as one example.
I have pipes on hand where the stem is thicker than 5mm, and I have pipes on hand where the stem is more like 3.5 mm. To the teeth and tongue, that's a mile. 5mm feels like a garden hose to me.
I won't argue with the people here who say "a pipe is a pipe". It's nonsense, provable by changing physical variables inside a pipe until it simply won't work anymore. People who are insensate to the difference between how briar and corncobs smoke, for example, mystify me. I find the experience entirely different. And that tells me that we are doing something very different, and our expectations are very different. It's not right or wrong, but certain people smoke a certain way and care about certain things, others move in different directions.
