From Wikipedia: "Many of the boletes are considered to be true culinary delicacies, especially the king bolete (Boletus edulis); the Scandinavian cuisine praises boletes. In Finnish cuisine, the king bolete is universally considered to be the tastiest culinary mushroom. A large number of boletes are delicious or at least edible. Poisonous or otherwise inedible species do exist, however, such as the unpalatable bitter species Boletus calopus and the aptly named bitter bolete (Tylopilus felleus) with a taste compared to bile, and some orange-capped species of Leccinum. As the bitter bolete resembles somewhat the king bolete, it can produce literally a bitter disappointment to the mushroom hunter. The rule of thumb is that the bitter bolete has pink pores, and a brownish stipe with a dark brown (sometimes approaching black) reticulum, while the cep has whitish pale grey, occasionally cream-colored to cream-colored with faint green tones, pore surface, a light-colored (white and/or similar in color to the rest of the stipe) reticulum and white hyphae tufts at the base of the stipe. If confused, the most simple solution is to taste a small amount of cap context.
If the taster detects a strong, foul bitter taste immediately or near immediately, it is Tylopilus felleus, unless, of course, the taster lacks the necessary genes to detect the chemical responsible for the bitter taste. They also grow in different habitats. The bitter bolete lacks the stuffed or plugged pore appearance (caused by a hyphal mat of cheilocystidia) that is common in the cep and allies. The peppery bolete (Chalciporus piperatus) has extremely strong taste, and has been used in place of pepper.
Finnish cuisine uses boletes for various soups, sauces, casseroles, and hotpots. They are sometimes also used as pizza filling, not unlike champignons, shiitake, or portobellos.
Two of the best common edible boletes, however, are the bay bolete (Boletus badius), whose pores bruise blue-green, and the orange birch bolete, which is a Leccinum with an orange cap and which bruises a bluish grey.
Several guidebooks recommend avoiding all red-pored boletes, but both B. erythropus (Neoboletus luridiformis) and Suillellus luridus are edible when well-cooked. One instance of death from Boletus pulcherrimus was reported in 1994; a couple developed gastrointestinal symptoms after eating this fungus with the husband succumbing. An autopsy revealed infarction of the midgut. Boletus satanas has also long considered to be poisonous, though it has not been responsible for any deaths. The symptoms are predominantly gastrointestinal in nature. A glycoprotein, bolesatine, has been isolated. A similar compound, bolevenine, has been isolated from the poisonous Neoboletus venenatus of Japan."