Infectious skin diseases constitute a significant public health problem. Despite the systematic development of many modern diagnostic and therapeutic tools, they still pose a serious challenge for clinicians. Due to their prevalence and mild course in most cases, they are often marginalized, which can delay their diagnosis and treatment initiation. Such an approach in more clinically advanced cases can have serious consequences, sometimes leading to tragic outcomes. This work presents a series of four cases of common infectious skin diseases with an unusually atypical clinical picture: the history of a 49-year-old female patient with recurrent erysipelas of the right lower leg co-occurring with a SARS-CoV-2 infection, a 75-year-old male patient with a generalized form of herpes zoster, a 38-year-old female patient with a complicated severe course of head lice, and a 34-year-old male patient with a severe form of post-steroid mycosis. In each of these cases, difficulties in making the correct diagnosis were highlighted, even though they represent some of the most common bacterial, viral, parasitic, and fungal dermatoses. The paper discusses the risk factors for these diseases, the pathophysiology of their atypical course, the effects and challenges in the therapeutic approach conducted. Infectious skin dermatoses require aggressive treatment and should never be underestimated.