  In this paper we consider the multi-dimensional pressureless Euler system and
we tackle the problem of existence and uniqueness of sticky particle solutions
for general measure-type initial data. Although explicit counterexamples to
both existence and uniqueness are known since \cite{Bressan-Nguyen}, the
problem of whether one can still find sticky particle solutions for a large set
of data and of how one can select them was up to our knowledge still completely
open.
  In this paper we prove that for a comeager set of initial data in the weak
topology the pressureless Euler system admits a unique sticky particle solution
given by a free flow where trajectories are disjoint straight lines.
  Indeed, such an existence and uniqueness result holds for a broader class of
solutions decreasing their kinetic energy, which we call dissipative solutions,
and which turns out to be the compact weak closure of the classical sticky
particle solutions. Therefore any scheme for which the energy is l.s.c. and is
dissipated will converge, for a comeager set of data, to our solution, i.e. the
free flow.
