When buying chicken from your local kosher butcher, what signs should one look for that would indicate there may be a question about the chicken's kashrus? Does it matter whether one bought a whole chicken vs. pieces?
While I'm inclined to believe that the certifying agency endorsement should be sufficient perhaps I am mistaken since the OU has new video related to this issue :
Together, they elucidate in a clear and thorough fashion the red flags in raw chicken that YOU need to know. After watching this video, you’ll have more confidence in the kashrut of the meat you serve.
And the Star-K notes that:
Education Breaks, Tears & Irregularities
Even with the best intentions and the most intensive hashgacha, problems can arise on occasion. Halachic shailos, questions, are addressed on a case by case basis. Nevertheless, general guidelines of what constitutes a shaila can be provided to the homemaker. A broken chicken bone with no discoloration, or slight discoloration and a jagged or fully broken bone, presents no kashrus problems; we would assume the bone was broken in processing. However, a broken bone that has begun to re-knit itself does present a problem. If there is a spot of coagulated blood without a break, the blood has to be washed away. If the break is surrounded by an area of coagulated blood, the chicken should be shown to a Rav.
Skin tears can occur in the plucking machine. If the bone is not broken but is dislocated from its socket, e.g., the drumstick or the wing from the chicken’s body, a Rav should be consulted. Similarly, a Rav should be consulted if there is swelling at the bottom of the drumstick, especially if there is swelling with red or green discoloration. It may not be evident, but there is a marked difference between a whole chicken and a whole cut-up chicken processed in the plant. If there is a problem with a wing of a whole chicken, the complete chicken is treif. With a cut-up chicken, only that piece should be thrown away because the cut-up tray is comprised of different pieces. In a local butcher shop, the housewife should check whether the cut-up comes from the same chicken or from various pieces that make up the tray.
The same is true with liver and giblets that are sold with the chicken. Those parts are packaged separately in the plant and are not the liver or giblets of that particular chicken. It is imperative to remove the liver pack before roasting the chicken. A chicken that is roasted with the liver in the cavity must be brought to the Rav for a decision regarding the chicken and roaster; the liver is probably treif and must be discarded. In certain processing plants, the necks are kashered with the whole chicken. In that case, the jugular veins should be slit three times or removed, and the mokom hashechita (the slaughtering site) washed off. At other facilities, where the necks are cut off, a machine clips off the mokom hashechita and the necks are kashered separately; splitting of the neck is not necessary.