If this fella is pricing against me and the finished work in his portfolio looks as good as mine yet my quote is hundreds more then it's not a surprise these cowboys can keep busy. Will look like the real tiler is trying to pull a fast one.
You need a print off of all these jobs that look good, but aren't. Show the customers when quoting why it can look okay and last a few months but will always backfire.
Wondering if this one was a plumber who did a bit of tiling too?