Could be the line claim, This Stren Stamina I use is for sure more of a leader material, really stretchy and very wear resistant. Some knots I’ve tried simply came untied. The heaviest mono main line I use, in saltwater, is 30#. Clinch works great.
I wanted to prove myself right so I did a little experiment and proved myself right…some of the time.
So to muddy the waters…
Test 1.
I tied a clinch knot with 5 wraps to clear and shiny 80lb (I think) mono to a stout shark hook and lifted a 45lb weight off the floor. The top knot was a plain simple square knot and both worked fine.
Then, I got greedy and added 25lbs to the test.
Test 2.
Same line and knots, the line broke at the square knot at the lift bar. Was it the knot or the line that failed?
Test 3.
New line, clinch to the hook with a short tag end and a double square at the lift bar…the clinch knot pulled free and unraveled. Grrrr.
Test 4.
New line, clinch to the hook with a long tag end and a double square knot at the lift bar…clinch knot pulled free and unraveled. 
Test 5.
New line, improved clinch to the hook and double square knot at the lift bar…improved clinch knot pulled free. WTF.
Test 6.
Clinch knot with 6 wraps with long tag and double square knot at the lift bar…line snapped in the middle.
Conclusion:
My 80lb test mono is crap. 
“I am constantly amazed at the stupidity of the general public.”
~my dad
Equipment:
190cc Sea Pro w/130 Johnson
1- 20 year old (boy of leisure)
1 - 17 year old (fishing maniac)
1 - wife (The Warden)
ECFC
Claim, interesting experiment. Thanks for going to that trouble.
But since the clinch seems to work for some, I wonder if there is something about their technique that makes a difference. Maybe a way to coil the wraps so it pulls down tighter? Another variable is how much pressure to pull on tag end? I think everyone wets line.
Whatever, I’m going with the alternatives, so long as they hold up. But again thanks for experiences shared.
Roger
Around 60 or 80 lb test is when I start using crimps. Buy some crimps and a set of crimpers. You’ll be happy you did if you find yourself fishing with heavy leaders fairly often.
Capt. R. Killin
“Day Tripper”
Shamrock 20 cuddy
Ford 351W
If tying heavy mono to a hook, then snell it by all means. When tying to a swivel, then a Palomar is one of a very few 100% knots, and it will easily tighten correctly in quality line up to 80#. Just make sure to use gloves to ensure a fully seated knot when tightening. You simply can’t top a Palomar for simplicity or strength. I have tied and tested thousands of Palomar’s in mono on a line testing machine and they simply do not break if tied correctly in quality line.
Other options that you can use in heavy mono if you do not need 100% knot strength are the Crawford knot, “commercial” knot, or a uni-knot. If you are using the 60# mono as leader material, then these less than perfect knots are perfectly suitable because their strength in 60# line or above, relative to the breaking strength of your main fighting line, will typically be greater (unless your main line is braid).
Due to the huge differences in the characteristics of modern lines (mono, flouro, braid, etc.) the most important thing is always to test your knot system in the house before taking it fishing. Tie your knot system to a heavy snap swivel, hook it to something in the garage, shield your eyes, then use gloves to walk away while holding the main line until something breaks or your can’t physically pull any harder. When something breaks other than the main line, work on improving that connection and then repeat the testing process until the system breaks in your main line or you physically can’t break it.