Yes having unused credit cards can affect your credit score in a bad way.
If you have too many unused credit cards then your credit score could go down and it can affect your credit score and credit history badly.
If you have a few extra unused credit cards then it may be best to close those credit cards or at least use the unused credit cards for even cheaper purchases that you can easily pay off.
To keep your credit score good you should use your credit cards and then pay the balance off each month or at least may the on time monthly payments.
Closing too many credit cards however can sometimes be bad as well and make your credit score go down some.
Also don't get into too much credit card debt and only use enough money on the credit card that you can easily pay back.
Being in debt too much with credit cards could cause your credit score to go down as well.
The average person's credit card debt is around $1,154.00 to $2,500.00
However some people may have even higher credit card debt such as my sister who is in debt to a credit card to the tune of $8,000.00
She was paying off the credit card as she was using it and making payments of $250.00 per month to the credit card company.
Then she suddenly lost her job and was unable to pay some on the credit card so she started paying just the bare minimum.
So she got into debt and still owes on that credit card and now she has a job and is slowly paying that off with $200.00 per month which right now is all she can afford.
So be careful spending money with credit cards as they can help your credit when paid on time but then they can get you in debt and you pay a lot of interest and then suddenly your income may be lost and you are unable to pay off the credit card and then it ruins your credit.