A bad credit score can result from little or no credit, high usage of existing credit or negative entries on your credit report. A landlord will likely never see your credit score (i.e. FICO) but may request a copy of your credit report. If your poor score is the result of negative entries on your credit report -- lots of late payments, collection issues, etc. -- yeah, that might be a problem.
That said, plenty of private party landlords won't pull credit reports at all. It can be dicey for a private party to access another private party's credit and they couldn't do it themselves (probably have to hire a service to check out your credit on their behalf). They'll look into using past residence referrals and income verification as measures instead.