It's ridiculously easy to be tricked, as an interviewer, in technical interviews. Tricked in both directions. Some people are stupendous programmers, but they have to look up everything (ever been asked to create a COM+ object from scratch without use of MSDN or the internet? Even a competent programming genius can have problems with this). Others will bring you code samples and say "I wrote this" and explain it in great detail, only to reveal later that someone wrote it for them and coached them through the whole thing (yes, this happened to me, dammit!)(but she was VERY cute).
The same goes for "pointing to apps they created." Unscrupulous people would point you to plagiarized stuff. It's WAY too easy to take credit for other people's work, or app storefronts.
The only REAL way to hire people and know their skills is to hire by trial. My favorite two ways of hiring are giving the candidates a competition task. I.e., write an app that does this. Then review the code. It's quicker, but a LOT of work for the interviewer reviewing the code if the task is easy enough and everyone completes it.
The other way to hire by trial is simply bring them on as a temporary employee (1099) until they prove their worth. This is the method that works out for me the best, although some interviewee's are skeptical, most of the good ones don't seem to have a problem with this.