Poor credit presents serious financial challenges, and renting an apartment can\may be one of them [but not always]. Some landlords don't check credit (in which case your credit rating has no effect). If the landlord is an individual (renting a converted basement or room, for example), you may be fine; at the other extreme, poor credit may cause landlords renting high-end luxury apartments to turn down your application. Most apartment complexes rent to people with poor/bad credit, provided there are some other factors in your favor that make you an acceptable risk [good employment history, more than one person on the lease, etc...].
I paraphrased from this article.