Just like lawyers, doctors and brickies, there are pilots and even checkies whose standards vary from excellent to marginal. The advent of the LCC has probably made no difference to the percentages of the good, the bad and the ugly. Back in the good (or bad, depending on who was paying) old days when there were two highly-protected airlines in this country, training cost was no barrier. But I still came across a few sub-standard pilots who had slipped through the net for years.
However, even the not-so-good can often scrub up just well enough to pass their regular checks. The checkie can only assess what he sees on the day.
Fortunately, for every dodgy captain there are 100 or maybe 1000 good co-pilots, and vice versa. So the odds of a safe flight are stilll pretty good.