Rangers frustrated the Royals by smothering midfield and by blocking off the runs of Reading's dangerous wingers Stephen Hunt and Jimmy Kebe, which have led to so many goals for them this season.
The referee was the focus of much discussion with Mr Foy rejecting two strong Reading claims for a penalty. At the end Royals boss Steve Coppell was seen animatedly talking to Mr Foy, presumably about the incidents.
The first-half claim was that Akos Buzsaky had grabbed hold of Kebe. The Mali international seemed to exaggerate his fall and that may have been what persuaded the referee not to give the foul.
There was a much stronger appeal at the start of the second half, with the ball clearly striking Gavin Mahon's forearm. Reading claimed the QPR midfielder had moved his arm towards the ball, but once again Mr Foy ignored their appeals.
Rangers were happy to play their stifling game, leaving Samuel Di Carmine to scavenge for a rare opportunity up front for the first hour, before replacing him with Dexter Blackstock.
The young substitute soon made an impact on the game - and Reading keeper Marcus Hahnemann in particular.
The America international failed to hold a fierce shot from Buzsaky and, as he collected the loose ball he was clattered by Blackstock. In keeping with his see no evil policy Mr Foy simply had a quite word with the Rangers player.
Thirteen minutes from time Reading came close to grabbing the winner from Stephen Hunt's corner, but Andre Bikey's powerful header went wide of the upright. They had an even better effort with five minutes to go but Radek Cerny made a brilliant save from Kalifa Cisse's header.
With Wolves and Birmingham winning earlier in the day this draw slipped Reading further behind the two Championship leaders, with tough trips to Burnley and Bristol City to come.
For Ainsworth the point was a very satisfactory start to what may still be a short managerial career as QPR choose the man to replace Iain Dowie.