Enquiring Minds... solution
by Kegler

The National Enquirer used to use the slogan “Enquiring minds want to know”.  The thirteen incorrect letters (shown below in red) spell out
YEN BECOMES KEN, which is, as indicated by the phrase in the shaded entries, AN EXAMPLE OF THE Y-TO-K PROBLEM.

Enquiring Minds solution grid

Across
9DUOS (SOUnD rev)
11A(Q)U + A [shadY s/b shade]
12T + ROUT
13VI(S + U)AL [orEs s/b orbs]
14EDDY (hidden)
16TULS + A (A + SLUT rev)
18VAL(U)E [daNe s/b dale]
19NOS + E (SON rev) [boB s/b boy]
21BOM + M (MOB anag)
23AM(B)ERica
25SHORE (HORSE anag)
29EDIT (DIET anag) [cuE s/b cut]
31E.G. + RE + SS
32WREST ("REST" hom) [Cull s/b pull]
33LURE (RULE anag) [rOle s/b rule]
34SATE (TEAS anag)
Down
1ALTERNATELY (TALENT LAYER anag)
2NERD (hidden)
3EX + OD(U)'S
4AUTOS (hidden)
5MOViE
6L + ASH [Mind s/b bind]
7EQUAL (hidden)
8F(ALS)EB + OTTOM (MOTTO rev)
10SI + EVE (EVE + IS rev)
15FUM + E [fEet s/b fret]
16TOrME
17AHS ("OZ" hom) [localS s/b locale]
20TRUSS (RUSTS anag)
22OR + DEAL
24BURRO ("BURROW" hom)
26HOW-TO (1st letters) [Kook s/b book]
27MEEK (WEEK with the W inverted) [mEld s/b mild]
28TSAR (ART'S anag) [aNt's s/b art's]
30I + S + LE