You won't hear jack with a dipole on either band.
That is pretty true for 2m, but not for 6m. I have gotten VUCC on 6m with an indoor dipole and worked Puerto Rico and Costa Rica with a mag mount mobile whip on 6m. During a good Es opening on 6 you can work a lot with a dipole. It isn't going to outperform a yagi, but it can still be a lot of fun!
I've been active on VHF weak signal modes for about 45 years and surely agree that when the 6m band is "open," a lot can be done with very little.
However, for the other 95% of the time when the band is not open, small antennas -- especially vertical ones -- typically yield a lot of "nothing heard here."
An interesting and somewhat eye-opening test which I've demonstrated hundreds of times is this one I run at home:
6m loop at 30 feet; Cushcraft Ringo vertical antenna at 30 feet; 7 element horizontally polarized beam on telescoping tower whose height I can change from about 28 feet to 65 feet by telescoping or nesting the tower. All low-loss feedlines brought to a 4-position antenna switch, so antenna changes can be made in less than a second.
Tune around with the beam at 65 feet, and with various beam headings, I can hear six 6m beacons 24 hours a day, regardless of propagation. (When the band's open, of course, there are many more in various directions depending on conditions at the moment.) But those six vary in distance from about 60 miles to about 300 miles, and they're always readable.
Now, switch to the loop: Two beacons can be heard, weakly, not nearly as well as with the beam.
Now, switch to the vertical: One beacon can be heard, very weakly.
Works this way every single day.
The antennas all "work," but the beam's advantage is so obvious that many are astounded.
So, on an average day with no special conditions (no sporadic-E, no any kind of ionospheric propagation), just tropo, I can "work" stations in about a 300 mile radius (about 283,000 square mile area). On the same average day, I can "work" stations in about a 60 mile radius using the loop (about 11,000 square mile area). The difference in the number of stations that might be workable is a ratio of 283/11, or nearly 26 to one, in favor of the beam.
That's why if 6m is "pretty quiet" using the beam, it can sound "abolustely dead" with a loop.