Pitiful...
One can read books and watch movies and do all the technical preparations, but a successful theft requires skills - and those you cannot learn from a book. Avoiding being viewed is one such skill; lying when asked about the toothbrushes is another. (There is no easy way for the store to prove, aside from watching, that this particular package was not bought elsewhere.)
That's why when a smart person commits a crime he often makes a mistake that is too trivial for him to even consider. (See Columbo, for example, or plenty of real life stories.) All those smart criminals are still green novices doing their first crime, but people who oppose them are doing the job for years and they know what to look for.