A DSLR needs sensor cleaning for several important reasons:

1. Image Quality: Dust and dirt on the sensor can cause spots or blemishes in your images. These obstructions can appear as dark shadows or light spots, especially in images with uniform backgrounds, such as blue skies or white walls.

2. Professional Standards: As a photographer, especially one specializing in portraiture or high-quality images, maintaining a clean sensor is crucial to delivering professional-grade work. Clients expect clear, blemish-free photos.

3. Longevity of Equipment: Regular maintenance, including sensor cleaning, can prolong the life of your camera. Dust particles can scratch the sensor over time, potentially requiring costly repairs or replacements.

4. Ease of Use: A clean sensor reduces the need for post-processing to remove dust spots, streamlining your workflow and allowing you to focus on the creative aspects of photography.

5. Visibility of Dust: In many cases, it is not until you take a close-up shot or use a small aperture (like f/8 or higher) that dust on the sensor becomes noticeable. Regular cleaning can help avoid unpleasant surprises during critical shooting moments.

For these reasons, it’s essential to keep your DSLR's sensor clean, ensuring optimal performance and high-quality results in your photography.