Some Walmart cards are considered of type "Consumer Finance" -- and such accounts may harm your score. I googled Is Walmart card consumer finance and this link came up near the top.
http://news.walmart.com/news-archive/2005/01/21/wal-mart-ge-consumer-finance-plan-to-issue-a-new-cre...
Some people on this Forum (certainly not all) seem to believe that some other retail cards, even if they are not explicitly classed as consumer finance, are likewise of mixed value -- compared to something like a major credit card (e.g. a VISA put out by Chase or Citibank etc.). If they are right, a long term strategy for someone with a bunch of "junk" card might be to identify the ones they really don't need or use, begin to close those out, and also begin to slowly intoduce more "high quality" cards into their profile over time.
I don't have a dog in that race, since I only have four cards and they are all premium cards not co-branded with any store.
I will relay one interesting piece of information, however. For several years I have had a closed store card appearing on my EQ and EX report. (but not TU). That closed account is MUCH older than all my other accounts, making my credit profile at EX/EQ much older than my profile at TU. I purchased my full slew of credit scores from myFICO a month ago, expecting that my TU scores would be lower than those from EX/EQ (the profiles are identical except for TU having a much shorter total age). But all three FICO 8 scores were almost identical, with my TU score actually one point higher. And looking at the older-model mortgage-based scores, my TU was MUCH higher than EX and EQ. Thus, having a retail card on my profile didn't give me any benefit, even though it increased my age a lot, and in the case of the older models might conceivably have hurt me.
