The colloquial Australian-English phrase couldn’t pick a seat at the pictures is used of an ineffectual person.

—Cf. also:
– couldn’t organise a piss-up in a brewery;
– couldn’t punch a hole in a wet Echo;
– couldn’t knock the skin off a rice pudding;
– couldn’t lead a flock of homing pigeons;
– couldn’t get a kick in a stable.

The texts containing the earliest occurrences of couldn’t pick a seat at the pictures that I have found indicate that this phrase was originally used in sports of team selectors—these early occurrences are as follows, in chronological order:

1-: From Sayings of the week, published in The Sydney Morning Herald (Sydney, New South Wales, Australia) of Saturday 25^th August 1984 [page 12, column 4]:

They couldn’t pick a seat in the pictures.
Peter Fenton, Sydney Rugby Union coach, on the national selectors.

2-: From Parrella loses patience with selectors, published in The Canberra Times (Canberra, Australian Capital Territory, Australia) of Thursday 18^th July 1991 [page 28, column 4]:

BRISBANE: Outspoken bowler Rob Parrella has launched a stinging attack on Queensland selectors, vowing never to play for the state again.
[…]
“We have players as good as any other state, but we have selectors who couldn’t pick a good seat at the pictures,” the highly successful Parrella said.

3-: From Basically, new Euro-Englanders are same old whingeing Poms, by Barry McKenzie *, published in The Sunday Telegraph (London, England) of Sunday 23^rd May 1993 [page 30, column 2]:

Cricketwise, we all know England have a small probbo with the selectors they have selected, who couldn’t pick a seat at the pictures. But they don’t have to be super-bright anyway because there’s nobody to pick from.

* Barry McKenzie is a fictional character created by the Australian comedian Barry Humphries (1934-2023).