In the wake of last week's general strike, El País published an opinion poll showing the PSOE over 14 points behind the Partido Popular. This was a significantly greater gap than most recent polls had shown. Following the general trend since the gap between the two parties started to widen, this poll didn't show any significant increase in PP support; the difference comes from the collapse in support for the governing PSOE.
This factor makes it even stranger that El País made no attempt to account for what is happening to those voters who have deserted the government. If the PP is only 3-4% above its vote in the last election, and the PSOE is 14% below then that means 10% of that fall in support is not accounted for. El País have taken to showing the results only for the two major parties, as if Izquierda Unida, the nationalist parties and UPyD didn't even exist.
Of course they are not the only ones who use polls to offer a distorted version of what is happening. The media in Spain are frequently accused of getting the results they look for from polls. In the case of La Razón, it is hard to find any evidence for the existence of their pollsters outside the pages of the newspaper itself; leading to the suspicion that pollsters and publishers belong to the same company and possibly share the same office.
Opinion polls are also published by a government agency, the CIS. The PP has frequently claimed that the results of CIS polls are manipulated by the government, although they seem to be quite a lot more trustworthy than many of those found in the media. Recently, the woman who was in charge of the CIS was replaced, allegedly because she refused to bow to pressure to change the time the organisation did its fieldwork in July to a moment potentially more favorable for the government. All of which boosts the credibility of the organisation, at least under its previous management.