I think AndyL makes a GREAT point - about the dirt. When using my keypad - AFTER I push the correct code I always push several other buttons to ensure I leave that "dirt trail" on ALL of the buttons!!!!
Also I don't think anyone is more paranoid than me - well OK maybe some of you are but not alot ;-)
So here's what I have done:
First off neither garage door opener works with the remote - I have one commericial roll up door - that I can operate with the pushbuttons - I set it up this way - you enter the code and that trips a relay - that relay enables the roll up door "open" switch - it doesn't automatically open the overhead door it just arms the switch to work. The "close" switch is always activated.
The relay is on a timer and only holds open for 20 seconds or so. That same relay activates the electronic door strike on the man door. I installed a commercial electronic door strike on my man door - if it's good enough for businesses with millions of dollars in inventory - it's probably OK for my little garage.
Next the other garage door is only functional when the lights are on. I don't trust the remotes - paranoid remember!? ;-)
So I have this all mounted in a weather tight box - It has the keypad and 3 switches. The "OPEN" switch only works the commercial rollup door. The 2nd switch (again only works when the relay is "ON") allows you to turn the lights ON or OFF - it activates a special relay in the light circuit. The 3rd switch closes the roll up door and again always works.
To open the front garage door - you need to turn those lights on and THEN use the remote OR a hardwired switch inside the garage.
I recently installed a commercial door closer on the man door just to ensure that it always closes and activates that door strike.
Also I set it up so that I can reach the buttons while seated in my car (drive up to it)- so while not exactly as convenient as a "normal" remote. I think it is much more secure. My buddy has had his garage door open when the weather changes - or someone else's code worked etc. Another buddy has told me he did some experiments with a RF generator and was amazed how many doors he could open - rolling code or not. So I feel my paranoia is partly justified.
Also I used mostly commercial pieces - you can piece part your system together from Ebay and have something far superior to what you will find at Lowe's or Home Depot.
YMMV
As far as the keypads - just make sure you have clean fingers, and don't leave the cover up (over time, finger oils + uv can make it really obvious which 4 buttons you keep pressing) .