The ones that cost the most.
NO CLEAR STATEMENT OF WHAT YOU DO
Visitors cannot tell within seconds whether they are in the right place.
HIDDEN CONTACT DETAILS
The most damaging and most easily fixed.
NO CALL TO ACTION
Pages that inform and ask nothing.
SLOW LOADING
Usually enormous images.
NOT WORKING ON MOBILE
Where most visitors are.
STOCK PHOTOGRAPHS
Recognised instantly, and they reduce trust.
TEXT TOO SMALL OR TOO LIGHT
Genuinely hard to read.
OUT-OF-DATE INFORMATION
Old prices, old hours, old staff, a copyright date from three years ago.
AN ABANDONED BLOG
Visible neglect.
A BROKEN CONTACT FORM
Losing enquiries nobody knows about. Test it monthly.
NOBODY MAINTAINING IT
The underlying cause of most of the above.
NO BACKUPS
Turning a small problem into a rebuild.
THE PATTERN
Almost all of these are cheap to fix and expensive to leave.