The problem is that we cannot know all the circumstances under which someone may try to observe the object (or detail in an object).
For instance, in order to say, "You should be able to see this.....", we'd have to know:
--the experience of the observer
--the size of the scope
--the magnification used
--the cleanliness of the optics
--the quality of the optics
--the quality of the seeing conditions
--the level of collimation in the scope
--the cooling of the scope (closeness to ambient)
--the altitude of the object above the horizon when viewed.
--the brightness of the night sky at the site
--the color of the star or object
--the transparency (i.e. extinction) of the sky at the site
--the exit pupil produced by the eyepiece
--the type of scope
--the age of the coatings and the type of coatings
--the age of the observer
--the quality of the eyesight of the observer
--whether or not the observer had drugs (prescription or otherwise) or alcohol in his system
--when during the night the observation took place
--whether the Moon was in the sky or not
--whether the observer was using a laptop/tablet/cell phone program to find an object
--whether the observer was completely dark adapted
--whether any direct lighting was visible at the site
--how tired the observer was
--whether the scope tracked or had to be manually moved
Where I grew up, the skies were modestly dark in my back yard. I had no trouble seeing all the Messier objects and hundreds of NGC objects
with a 4.25" reflector. Yet, I read of people having a hard time seeing this or that Messier object with a 10" scope! The difference is almost certainly
the darkness of the sky, so could I say all the Messier objects would be visible in a small 2" or 4" scope (they're all visible in a 50mm finder at a dark site)?
Well, certainly in dark skies, but many modern observers don't observe in dark skies and have to travel hundreds of miles to get to them.
So I don't think I can safely say that all the Messiers are visible in scopes of that size.
So perhaps we should say, "This is what I saw," and try to specify the scope and conditions so others may relate.
I know if I could ONLY observe in my backyard in L.A., I'd be a lunar/planet/double star specialist and simply stop observing anything else.
I live in a White White Zone, where the night sky is kind of like a permanent twilight and never gets dark.
I have access to dark skies by driving, though. Should I assume that someone else does not?
Should I assume the individual asking about the visibility of a particular object is living under skies as bright as mine?
Or should I assume the observer CAN get his scopes to dark skies?
All these factors will influence the relevance of a reply.
The one thing I always tell newbies is this:
"You will never see less than you see right now. As you gain experience, you will see more--more details, more faintness, more objects. There is no experience
in which you can participate that will teach you how to observe a deep-sky object through a telescope other than observing through a telescope. Observe,
and observe again, and observe some more. A year from now you will go back to view the objects you could *barely* see when you started out, and you
will find them bright and detailed. Were you blind? No. You were just inexperienced."
How do you get to Carnegie Hall? Practice.