I think the great majority of these deaths are accidents. Many men like to pee in rivers and lakes for some reason, no one pees more often than people who've been drinking (especially those who're drinking beer!), and it's easy to slip and fall when you're unsober. Reports revealed that several drowned men were found with nothing unusual about them besides the fact that their flies were unzipped; apparently they'd fallen in while peeing!
I also suspect that some unsober people are irresistibly drawn to sparkling water, in the same way as severely autistic children (who when missing are commonly drawn to water and sadly often end up drowned). Everyday things can become abnormally profound and fascinating with chemical influence: have you ever stared transfixed at the night sky or even the pattern of the ceiling when you were just DRUNK?
When this happens in the summer or in some place like Florida, it's easier to get out and so hardly anyone dies this way; whereas with the supposed "Smiley Face Murders" it is so cold in these areas at these times of year that hypothermia sets in VERY QUICKLY.
Hypothermia, actually, is what I suspect is behind the bizarre behavior of some "victims." They could hallucinate that people are after them, and then do illogical things like break into buildings to hide from the imaginary pursuers. Hypothermia would also explain the fact that some "victims" were found in various states of undress, because hypothermia paradoxically makes you feel overheated. That would certainly explain wading into the frigid water: what better way to cool off to a delusional mind?
Several "victims" might still be alive, had not the bar security kicked them out in cold weather without their coats. In these cases, the bouncers are criminally negligent or something, certainly at fault, though likely not murderous or in cahoots with the real killers (as many on The Internet have suggested).
A handful of these cases are certainly murders, like Patrick McNeill. He didn't fall in while peeing! The disappearances that are possibly connected with vans MIGHT be a serial killer thing, but if so, they are far from the prolific ingenious murderers some people say they are.
"Muggings gone bad" is a more logical explanation in absence of good evidence that the Definitely-Not-Accidental-Drowning deaths are the work of the same killer(s).
Several of the suspicious deaths seem to me to be cover-ups by friends and/or acquaintances after the victim had died accidentally from alcohol poisoning or overdose. Especially when you're into illegal drugs or even underage drinking, it might seem like a better idea (at the time) to dump a body in the river to be blamed on the SFK, rather than to be honest and call the authorities.
Reasons that the "victims" are all men include
1) We women are much stricter adherents of the "buddy system" because of the real threat of rape (PARTICULARLY in situations involving alcohol and other drugs). Typically we do not let our drunk friends stumble down to the water's edge for any reason, nor do we leave each other black-out drunk at the mercy of male strangers.
2) Women are more reluctant than men to pee outdoors, but when we have no choice a river or lake is the last place we'd pick. Whereas in my experience, men will pee into creeks and on trees for the sheer joy of it.
3) Because rumor has it that the "Smiley Face Killers" only kill college age men, if you're looking to cover up a woman's accidental death, it wouldn't work as well to dump her in the river and let it be attributed to the SFK.
Anyway, the smiley faces are almost POSITIVELY irrelevant. That symbol is everywhere! I also expect that the bulk of the smiley faces were really drawn by bored/mischievous kids AFTER a drowning hit the news.
If the smiley faces were painted or carved into the corpses, it'd be a different matter! But they're not, they're merely found as graffiti on buildings, trees, and/or rocks near where the body was found AND/OR they're near where the body MAY HAVE entered the water. Or they're found some place even more obscure, like in the bar on a guitar-player's T-shirt!
Likewise, the NUMEROUS "connections" or "codes" or "clues" or "messages" or whatever concerning the names of streets and the names of cities and the names of the dead are all UTTERLY MEANINGLESS COINCIDENCES. The human brain automatically looks for patterns and for meaning, but if we're not careful to respect logic, we can end up "seeing" patterns where there are none and meaning in nonsense. (I mean no disrespect to the people with pages-long "hidden clue" analysis; they clearly worked very hard at it!)