Personally, I feel the Romero zombies (those in Night of the Living Dead in particular) were pretty creepy, more so than most zombie depictions I see today, mainly because they didn't do things that broke my suspension of disbelief all the time (i.e. making squealy pig/weird animal noises impossible for humans to make, being completely bullet proof, among other things).
Anyway, to address Qarim Trablusi, 2 things. 1. 100% infectivity doesn't need to be an artifact of the eldritch gods; measels, for example, has a near 100% infectivity in those susceptible to it (people who haven't been vaccinated), and some diseases have 100% mortality without treatment (i.e. rabies).
2. Depending on the physiology of the zombies and the nature of the pathogen, I think the zombie plague could still be a formidable, population decimating problem even if the resulting zombies were slow, could rot, and had no special physical attributes. I think key to this happening are four things: persistence of the pathogen in the environment with huge resistance to degradation, the ability of the pathogen to be passed through feces (in addition to typical zombie trope routes of infection), the ability of the pathogen to be harbored in other species we have close contact with (especially birds, mice, cockroaches, or livestock!) causing no/attenuated pathology, and the incubation period of the pathogen being variable (from days to weeks or even months/years). The pathogen being airborne would be a plus, though it would go against the typical zombie trope.
Say the zombie plague was like scrapie in that it is resistant to degradation (as in, resisting high amounts of radiation, heat < 600+ degrees C, strong acids, bleach, etc… scrapie is scary shit!), can be passed through poop, and is harbored in domestic/common animals. It could persist for a very long time in the countryside as well as in a city, and could pass rapidly through the water supply if enough people get infected and poop into the sanitation system. One could be infected by interacting with an infected animal, not even needing to be bitten or anything (licked by an infected dog, milking an infected cow, stepping on infected bird poop and carrying it into the house, etc.). If the incubation period were variable and could be somewhat long (like a few weeks or months), large amounts of people could get infected and disseminate it and not even know it, until a certain time hits, and, boom, hundreds of zombies. In an urban center, this could be catastrophic and spread easily. Even with a short incubation period, if the infected are ambulatory (and zombies are!), then the infection could still spread fast. Hmmm…