Buying at Wal-Mart/X-Mart is a hit-n-miss proposition. Some things are acceptably good, others are trash. And there is no categorization of these things. (Except bikes, of course -- across-the-board crap, and this is from one who assembles them)
My buds and I have caught the photo-oops'es from several big-box store ads. Always good for a laugh.
Last year, there was some talk about W-M opening clinics in some regions; we had a field day with that one, talking about the shaky-handed people greeters at the door hobbling your way with a latex-gloved finger extended....
Now, there is a segment of the population that really has to depend on W-M and the like for their bikes, as the 'premium' child bikes I see start at $190. A bit much to get lil Corky out on two wheels for most people....
My daughter is about to get her 5th W-M bike (massaged and upgraded by her mechanic dad, o'course), and I have yet to pay as much for all 5 as I paid for the frame/shock on the bike I ride now (which I got half-off). Nothing has broken or failed under her, and each one lasted 2-3 years (well, except for the last one, she outgrew it in like 7 months, but it still works like new). 3 have been passed on to younger children in our circle of family & friends.
But what does get me is the crowd that comes in and thinks out loud that you can get a helluva good bike for $100. Sorry, but this isn't 1970. I corrected the last one, telling him, "No, you can't get a good bike for that -- what you CAN get is one that'll likely not fall apart under you inside of an hour."