The problem with playing junk hands like 8/3o is that if you hit it big it's not likely to help your opponents, so you don't get a lot of their chips in.
People play big hands for big pots, and what gives 8/3 a big hand is not going to give most openers a big hand.
So while you lose small pots over and over again as you draw, you do not win big pots when you win. So overall the wins do not compensate for the losses.
I mean, the flops that are going to be good for your 8/3 will be 8/8/x and 3/3/x and those cards are not likely to connect with people who raise pre-flop. Also, paired boards are an obvious danger so the villain is going to be more cautions about playing for a big pot. That's why set mining with small pairs is better, because when you do make a big hand it's disguised *and* if one of their cards flops or turns trips (a big hand) your set has turned into a full house, so you're likely to get his stack in.
If you have 8h/3d with a 8s/3h/Ad flop, and the villain has As/J+s, you might think "jackpot!" But the villain is going to draw out a win about 30% of the time.
But with thirteen different cards in the deck, and your opponent having two, how often will one be the X? Not very often.
Even if your opponent has a pair like T/T that Ace is going to scare him into keep the pot small. Heck, if the flop was 8/3/2 rainbow a scary face card will hit the board on the turn or river nearly 2/3 of the time (killing action) and he'll outdraw you about 25% of the time.
Basically, playing junk needs to hit ideal situations to win really big. Those situations do *not* come up enough to justify putting money in with those hands.
If you look up people's play statistics, the people who see the most flops are usually the biggest losers. There is a reason for this, and it's not bad luck.
If your friend says, "I meant limp with the junk hands on rare occasions" that's still bunk. You're going to hit the flop at the same rate and still have the same expected negative return.
Now, however, if you*raise* with junk on occasion that is a different story. This puts it into the realm of a bluff. You can win by taking the blinds pre-flop. You can win a big pot when you do hit hard because your hand is disguised because nobody opens with 8/3. You can also win because your raise indicated strength so you can take the pot on the missed flop with a continuation bet. Basically, you have a lot more ways to win.