We present an experimental spectroscopic study of large random colloidal aggregates of silver nanoparticles undergoing local restructuring. We argue that such well-known phenomena as strong fluctuation of local electromagnetic fields, appearance of "hot spots" and enhancement of nonlinear optical responses depend on the local structure on the scales of several nanosphere diameters, rather that the large-scale fractal geometry of the sample.Physical properties of surface plasmons (SPs) in disordered nanosystems have been the subject of intense studies in the past decade [1,2,3,4]. The two objects that attracted most attention are disordered two-component composites [5,6,7], including two-dimensional percolation films [8], and aggregates of nanometer-sized noble metal spheres formed in colloidal solutions (colloidal aggregates) [9]. The latter are subject of this paper. Optical and, more generally, electromagnetic effects that were discovered in colloidal aggregates include giant enhancement of nonlinear-optical responses [9, 10], inhomogeneous localization of electromagnetic eigenmodes [11,12], and optical memory [13,14].