Long pants or short, once it’s warm enough for Tevas, the shoes get put away.
Wear whatever you want is how I feel about fashion, but please keep the toenails trimmed!
This was apparently a look that was popular with some kids several years ago-- my wife and I went to her nephew’s grad party and two of his friends were wearing sandals with black socks almost to their knees, with little Nike logos on the socks. They also wore ball caps with completely flat brims. The overall look was impressively dorky.
Agree!
I’ve almost entirely abandoned jeans in favor of a more casual pant - like loose fitting Dockers. Living in the desert, you want to keep the sun off your skin so I’ve found Dockers infinitely more comfortable in the summer. So it all comes down to whether I feel like putting on socks - socks on/sneakers or socks off/sporty sandals. I also have a pair of ‘water shoes’ I’ll slip on for some occasions.
Particularly white crew socks.
Fisherman pants, or yoga pants, or whatever you want to call them:
I doubt anyone will complain they are too dressy for sandals.
Those look like Aikido pants
I’m super susceptible to sunburn so I wear long pants and long sleeved shirts pretty much any time I go out. I’ve found Columbia’s Silver Ridge pants and Silver Ridge Lite shirts to be extremely comfortable in warmer weather…and they look good with sandals, too!
Don’t know what’s prescribed for Aikido—I am talking about those unisex, one-size-fits-all, fisherman pants, typically light cotton, sold at the market for $10 or less. I suppose you could use them for martial arts practice, or yoga, or anything similarly requiring flexibility, in which case you would probably be barefoot.
Speaking of Men In Sandals, I was with my gf years ago to see Amy Rigby perform. My gf was invited to the after show meet and greet and I accompanied her. We were standing around talking, and there came a time when I was asked to run to the car to get something for Ms Rigby.
I acted put upon, saying, “you want me to run to the car after what she said about my footwear?” Everyone looked in unison at my feet, which were in sandals. (She sang a song called Men in Sandals which made fun of men in sandals)
I admit to having done this, at least if you count Crocs as sandals. When I have, it’s a matter of being lazy rather than any attempt at a fashion statement. It happens when I take my shoes off, but not my socks due to being too lazy to take them off. Then if I have to get up to do something like take the dogs outside, I’ll just slide on my Crocs while still wearing socks.
Get some deck shoes 
I wouldn’t be likely to wear this combo, but that’s just because if it’s warm enough for sandals, it’s also warm enough for shorts. But I will confess that, when I’m lectoring at church in the summer, I’ll usually wear dress pants, a short-sleeved dress shirt, a tie, and sandals. Because nobody’s even going to be able to see my footwear, up at the lectern.
As for socks, ugh, the whole point of sandals is that you can wear them without socks. Who the heck wants to wear socks in the summer?
@Chronos just said exactly what I was going to say. I probably wouldn’t wear that combo purely for practical reasons. If the weather is cool enough that I’m wearing long pants, then it’s too cool for wearing sandals.
As for other people wearing that combo, I really don’t care what other people wear.
I live at the beach and other than work or exercising, rarely wear anything other than flip flops in the summer. Jeans and flips into October is common. If an event calls for long pants but is still somewhat casual, most men will be wearing nice flip flops or sandals. No one will look twice. And if they do, they can go back to wherever they live the rest of the year. 
I can visualize “worse” flip-flops, but not “nice” flip-flops
A revelation as shocking as not caring how other people cook their steaks. 
I was gonna say - get enough years behind you and you wear what is comfortable, not worrying what anyone thinks about it. I’d have to think Tevas or Birks w/ jeans one of my lesser fashion faux pas!
In summer some of my coworkers wear socks with sandals. Either Birkenstocks, Adidas slides or safety sandals. You wonder, why bother? Because normal safety shoes are extremely warm and don’t allow the feet to breathe, so safety sandals fit the requirements.