Oh come on ... I'm old enough to remember the 1979 Tory poster of an unemployment queue with the quote "Labour isn't working". What about the boxing gloves regarding Labours tax "Double Whammy"?. How about the worst of all, the poster of Blair with devil-esque eyes? It's not just Labour who are doing this kind of electioneering. I think you'll find that the big parties look to slag the others off without promoting their own alternatives.
Take the unfortunate announcement today regarding Peugeot in Coventry. The Tory spokesman said "It was thriving under a Tory government" - if you count years of union supression, little investment and courting of Japanese manufacturers as "thriving", then yes, it was. The fact global market forces are at work and it simply costs less to build the cars elsewhere is lost on the Tories now - they'll just blame Labour.
So it's not just a Labour phenomenon - they're all it and have been for a long time now. You just have to get used to it, read a variety of media sources and use your own judgement to make up your mind in the polling booth. Sadly, it's not as simple as voting for a shirtless wonder on Pop Idol which means that a large proportion of the nation doesn't bother.