Retouching to clean a photo can give some headache, but it gets even more difficult when the picture has some tiling texture and is in perspective, as an example a wall. To solve this kind of problem the Varnishing Point filter is a perfect helper.
Before starting make a copy of the image you want to fix on a new layer: you can easly do that by pressing Ctrl+J or Cmd+J. Then from main menu choose Filter/Varnishing point and get into the filter's window.
Step 01. On the left of the Varnishing Point window, choose the Create Plane tool, then make 4 clic on the picture to draw the 4 angles of the plane. Please take care that the plane you create should correspond to the plane of the area to fix: if the grid of the plane in displayed in blue it means that you did a good job, if it's in yellow or in red it means that the perspective is not correct. To fix the plane just drag and drop the angles.
Step 02. Once the plane is displayed in blue you'd need to enlarge it: to do that just drag and drop the points you find at the half of each side.
Step 03. When the working plane is defined you can start with the retouch. Choose from the tools the Stamp tool. To display the brush shape you need to define a source to clone, to do that keep pressed the Alt key and do one clic on the image. Once you define the source you will have the brush preview: this way it's easier to adjust the size of it with the Diameter value. Keep the Hardness around 60/70 for a soft but precise result and from dhe Heal drop down menu choose OF when you have to fix a really dirty area as in the sample. Switch on the option Aligned.
Step 04. To retouch the dirty parts you need to clone a clean area and overlap it on them. Because you're going to "rebuild" the area to fix, you need to have a cloned part that have the same design: for example don't use as a source the border of the tile if you need to fix the center of it.
Keep pressed Alt and choose a source area, then drag the mouse to patch the dirty part. During the job, you can set diverse sources.
Finish. Because we turned off the option "Heal", probably some of the cleaned parts will look strange and not perfectly in line with the area around. To fix them from the top bar choose ON in the drop down menu Heal and retouch them again: they will be recoloured and better integrated with surroundings.