They're always the best example of what not to do with funds you receive from selling your players to bigger clubs.
Main players sold since summer 2009: Knight (£4m), Barry (£12m), Milner (£26m), Downing (£20m), Young (£16m)
And where some of that money has gone: Warnock (£7m), Ireland (£8m), Bent (£18m), Makoun (£6m), N'Zogbia (£10m), Hutton (£4m), Lowton (£3m), Kozak (£5m), Okore (£4m), Sanchez (£5m), El Ahmadi (£2.5m), Tonev (£2.5m), Bacuna (£3m), Jensen (£2m), Bennett (£2.5m), Sylla (£2m), Beye (£2,5m), Cissokho (£2m).
Including those £2m - £4m amounts is important, because they quickly add up (plus all of their wages). And pretty much all on players who don't get a kick (and/or have since been sold at a loss). Benteke, Delph, Downing and maybe Given, Dunne and/or Vlaar are the only successes they've purchased during this six year period, before now.
And if you go back another year or two, you also find that they ultimately made substantial losses on Reo-Coker, Davies, Young, Heskey, Harewood, Friedel, Sidwell, Shorey and Cuellar.
[Figures as per
http://www.transferleague.co.uk/aston-villa/english-football-teams/aston-villa-transfer]