While many users look for sites like Gogoanime, it's often smoother to use official platforms that support the creators and offer high-quality, ad-free streaming. You can find Gintama Episode 88 on:

Episode 88 is from 2008. The raw file on Gogoanime is likely a 480p encode from a DVD rip. It won’t look awful, but don’t expect Blu-ray clarity. For a comedy episode based on visual gags (like Hasegawa’s hollow eyes), this is usually fine, but purists may be disappointed.