Are trainers useless - yes & no - DEPENDS ENTIRELY ON THE TRAINER AND YOUR GOALS.
I am a trainer, but I stand out in my gym not because of my size or definition ( there are guys way bigger and more ripped than me ) but due to my knowledge.
It all depends on what you want your trainer to do - a basic workout, bodybuilding, sports training or rehab. Most trainers specialize in one area or maybe 2
I spend thousands of dollars on education, certification and specialized training programs so I can handle multiple areas. I also spend hundreds of hours :watching training technique videos, video lectures on nutrition etc. Reading books, journals and mags. I also spend hours searching and reading posts at Elite Fitness for the latest drug & supplement info.
Most trainers can do the basic workout and diet - I found that to gain the respect of the "big" guys and the average member I had to be able to instruct on any level (show them some kick ass exercises - not these bullshit machines!) and be able to answer their questions including different cycles & supplements etc.
Your best bet is to talk to a few, if they don't know shit about diet, supplements, drugs - pass on them. If they only show machines and very basic exercises and perform no sort of movement testing and evaluation - ignore them, you can learn more from a book or video. To start a workout routine with no postural, movement & flexibility assesments will just lead to poor form and injury later on - I AM SPEAKING FROM PERSONAL EXPERIENCE!! - I am paying for a lot of ART therapy due to my early meathead days
If they only have an ACE certification and read muscle & fitness - take them outside and kick their ass! - Also kick the ass of the moron who hired them as well because he/she must be an idiot and knows nothing about training!
Things to look for:
College education, work experience, sports background
Certification by: NSCA, NASM, CHEK, or USAW (these are the top organizations for practical training & assemsnts; but they don't provide nutrition or drug info)
What do their clients look like - can they show you before & after pictures with testimonials of CURRENT members who you can contact (some trainers don't look as good as their clients because they spend more time training others & studying than working out - although they should not be FAT!)
Can they honsetly and intelligently answer your questions, yet be humble enough to refer you to an expert in situations where they can't help?
what is their reputation among members and the staff, it should be a mix of admiration, trust and dislike - dislike in that the trainers and members who don't know shit (>90%) and are too stuck up or narrow minded and will be enveous and jealous of the top trainers.
Do they train with themselves with free weights (takes more knowledge, skill, motor control & coordination than using machines)
Do they full squat, bench press, deadlift & do pullups and dips? Can they properly teach olympic lifts? - These and their derivatives are the best strength, mass exercies and have applications in most sports and rehab situations AND THEY WORK WELL WITH WOMEN AND THE ELDERLY - ALBIET AT LOWER LOADS & INTENSITIES!
These are just some things to think about!
Later!