Good rental history, bad credit

[Bienes Raices]

I have some good tenants with bad credit (one is below 500). They told me they always pay their rent, just not their other bills, and I verified this to be true. They've been in the unit for almost 2 years now with few issues.

But, for future applicants, I'm wondering what types of creditors can come back and garnish their wages at some point in the future, decreasing their ability to pay rent? Can credit cards and hospitals do this? Garnishment is something I know little about. Thanks.