I think that hype is to a degree inevitable given the technological advances e.g the internet that marketers can now use. In a way (however limited) the stuff they use nowadays - a minimum of 10 'teaser trailers' before a actual trailer is just a natural technological evolution from the old marketing techniques that guys like William Castle or exploitation showmen used. Don't tell me that William Castle wouldn't have a field day with the tech we have now. Though perhaps he would do it in a more innovative manner
In a way though the situation has reversed. Before lower budget/exploitation films used lurid and relatively cheap, but simple and often effective marketing to attract attention but now its the more mainstream and higher budget studios who have the cash to spend on expensive and clever marketing campaigns. Though films show that with a little hard work and persistence even independents can gain momentum and attention.
Now does hype ruin film's, yes it sometimes does. Two recent examples I can attest to myself are Cabin In The Woods and V/H/S. Do I think it is better to judge a film without the context of hype around it. Yes I do. Is opinion subjective and can we completely avoid it. Yes and No I am afraid.
The good thing about film being available on VHS/DVD and now Blu-Ray is that we can re-watch films, hopefully without the past hype so attached to it as on initial release. There are load of films within the horror genre that were established classics but I were not impressed with on a first watch. However watching for a second time I now think they are masterpieces. The most obvious example that can come to mind is the very first and original Evil Dead.