Select exactly what you need in seconds. Selector picks every shape like the one you've selected, matched on size, colour, stroke, opacity or type, and has one-click selections for guides, open paths, clipping paths, stray points and more.
See it in the shop · Version 2.1.6 · Needs PowerScripts 3.8.42 or later
Open the PowerScripts panel (Window > Extensions > PowerScripts) and choose Selector from the Tools scripts.
To select every red circle the same size as one you've picked:
Select one shape, tick what has to be the same, and press Select Matching. Everything that matches on all the ticked boxes is selected.
One click selects all of these in the document:
0.5 x 0.5 mm to find specks, check them, then delete.