If anything, they should be flattered that they were asked to be used as a reference and trusted, too. But, people will be people. On the other hand, it is not advisable to use supervisors or bosses who did not give good reviews or who were overly critical of the individual. Do not give personal references such as mother, father, cousin, sister or aunt. This looks silly and is not professional.
Common sense works well when it comes to references.
An individual should remember to ask politely and know the person long enough before asking for the reference. Make sure good contact is kept between the two people, as people move and phone numbers change. A nice suggestion is to take the reference out for coffee and bring it up or just approach it in a positive and flattering way. Usually, people are receptive. If the person is not receptive, it s not a good idea to push.