A quick search on Google is sure to reveal that the idea that "everything is suffering" persists amongst Buddhists. This misunderstanding of the Four Truths of the Noble Ones* has been particularly tenacious and pernicious. It has lead some people to label Buddhism as nihilistic, though such an idea is clearly bonkers. However the fact that the misunderstanding persists amongst Buddhists does not help. The arguments usually goes that because every thing (thing in the sense of an object of the senses) is impermanent and insubstantial (anicca and anatta in Pāli) that we suffer. All conditioned things are impermanent, therefore all conditioned things are suffering.
In his Survey of Buddhism (p.142ff) Sangharakshita makes an important contribution to understanding the truths of the Noble Ones. He points out that the Buddha made a distinction between doctrine and method. The charge of nihilism is a categorical mistake: the truths of the Noble Ones are methodological rather than doctrinal. This is evidenced in Sariputta's discourse, the Sammadiṭṭhi Sutta. In this sutta the content of the first Truth is shown to be unfixed. Suffering can be replaced by food, birth and death, name and form, or ignorance. The doctrinal principle is dependent arising. The truths of the Noble Ones are an application of that doctrine to the problem of suffering. Suffering is a good starting place, Sangharakshita tells us, because as an experience it is ubiquitous. Also being a experience it is not so susceptible to being intellectualised. Meditating on a concept is far less efficacious than meditating on an experience.
The matter is made quite clear in the saṃyutta nikāya in a sutta addressed to a layman called Mahāli (S 22.60 = S iii.68ff). Mahāli has been talking with another spiritual teacher who claims that there is no cause and effect, no reason for "defilement" (saṃkilesa), and therefore, by implication, no reason for the problem of suffering. Shit happens. The Buddha tells Mahāli that there is indeed a cause for suffering.
Forms are neither exclusively unpleasant (dukkha) nor are they exclusive pleasurable (sukha). The same is true of feelings, perceptions, volitions and consciousness - ie the five khandhas (Sanskrit skandha). If everything was suffering then beings would not become attracted to anything. But because experience has a pleasurable aspect we do become attracted to it; and being attracted we do become captivated by pleasure; and being captivated by pleasure we are defiled, which is it say we suffer. There is good sense here. If everything was suffering then how would be become trapped in desire for experience since no one, ultimately not even the masochist, desires suffering? The charge of nihilism was never sensible, but it should obvious from this sutta that the claim that "everything is suffering" is also not sensible.
The Buddha tells Mahāli that the converse is also important. Because if everything was pleasurable then there would be no way for us to become disillusioned with experience, and to seek a way beyond birth and death. It is only by withdrawing from obsession with sensual experience that liberation becomes possible.
It's all too easy to get caught up in various kinds of literalism. This is an aspect of what the Buddha is telling Mahāli. Ideas are attractive, we become captivated by them, and we start thinking that ideas, or opinions about things are real, or true (the same word, sacca, is used for both in Pāli). Any kind of absolutism is likely to be a fallacy. In fact any kind of strongly held opinion is likely to be a fallacy, or based on one. This is why focusing on experience, as the Buddha so frequently does, is so useful. Suffering is not generally a matter of opinion. It would be nice to think that having pointed out an error, the error will be eliminated, but this is all too unlikely given our intoxication and obsession with sensual experience. Hopefully the Mahāli Sutta will at least stimulate some reflection.
There is a translation of the Mahāli Sutta on Access to Insight. In Bhikkhu Bodhi's translation: p.903f (single vol. ed.)
* The great philologist K.R. Norman has shown that "Noble Truths" is unlikely to be the correct translation of ariyasacca, and that truths of the Noble Ones is far more likely. I have therefore adopted this as my standard translation.