Camden county is rough with the linear simulcast distortion. Even if you are within the coverage area the audio coming out of a scanner is usually crap. You may need to upgrade to the SDS100 or SDS200. Supposedly these new scanners can handle the linear simulcasting. You shouldn't have any problems hearing Burlington County with the 436 with default settings so long as you are within range of a local site.
I have noticed with the scanners, if you have all sites on the system enabled, that they will lock onto the first site it can decode even if it is on the fringe of coverage and pass traffic from that site. The signal strength from the voice channels will be poor resulting in choppy distorted audio. This requires you to force your scanner to another site with a better signal. I believe on the 436/536 scanners you can setup RSSI thresholds for site switching. If so this requires some experimentation and tweaking to get it right.
You're probably thinking of old GRE scanners. Uniden doesn't have any RSSI switching. It's using a site as soon as it manage to open the squelch. If the system use different frequencies for different sites, and are not a simulcast system, you probably would like to lock out all sites except the strongest one.