Does Postgres ever require a naked field without single quotes? I have this query:

UPDATE user_map_table SET  user_id = '1', value = '{"bob":"diane"}', key = 'couple', value_type = 'string', added = 'false' WHERE user_id = 1


it worked fine. The thing is the user_id column is an int column, and the added column is a boolean column. Postgres doesn't seem to care that I put single-quotes around the '1' and 'false'.  Is there ever a time where single quotes will make Postgres barf?

One obvious answer might be if you have extra whitespace:  ' 1' or 'false ', but other than that?
With overloaded functions (same name but different arguments), there can be cases where they mean different things. But you should probably avoid creating such cases.

create function j(int) returns int language SQL as $$ select 1-$1 $$;
create function j(text) returns int language SQL as $$ select 7-$1::int $$;
select j('5');
 2
select j(5);
 -4