Hey there 0memo0,
It sounds like you have some concerns about your Touch ID sensor being discolored. If you've already cleaned the phone using these guidelines:
iPhone 5s
Clean iPhone immediately if it comes into contact with contaminants that may cause stains, such as ink, dyes, makeup, dirt, food, oils, and lotions. To clean iPhone, unplug all cables and turn it off. Use a soft, slightly damp, lint-free cloth. Avoid getting moisture in openings. Don't use window cleaners, household cleaners, aerosol sprays, solvents, ammonia, or abrasives to clean iPhone. The front glass surfaces have an oleophobic coating. To remove fingerprints, wipe these surfaces with a soft, lint-free cloth. The ability of this coating to repel oil will diminish over time with normal use, and rubbing the screen with an abrasive material will further diminish its effect and may scratch the glass.
To clean the Home button (allowing Touch ID to work optimally), wipe it with a soft lint-free cloth.
How to clean Apple products
http://support.apple.com/kb/ht3226#iphones
I would schedule an appointment at a local store to have it evaluated:
iPhone Repair - Other Repairs
https://www.apple.com/support/iphone/repair/other/
Thank you for using Apple Support Communities.
Cheers,
Sterling