I'm a grad student working in a lab, coincidentally the same lab I volunteered in as a premed.
Luckily, our lab manager is a no bull kind of guy and chewed me out for being a premed during the tour. It was enough to set off my "I can prove you wrong" work ethic.
So getting bitched out and then having the opportunity to see from the point of the grad student, here's my two cents.
Grad students spend SO much time in our labs. They really are ours, this is our life and blood in this research. Also there is always heavy pressure to produce meaningful data. To get to that data into a publication takes years of work, countless failures, and countless redirections of the lab. Simply training someone on the protocol is going to be a good amount of time trouble shooting. There is also a possibility that there is the red tape jungle to get them on the protocol if the lab works with animals.
So the premed walks in because they've been told by everyone that medical schools see research as little gold nuggets on your resume. They want publications, they want hands on experience, they want leadership positions, they want a line on their resume, and a letter of recomendation. Which is fine if you earn it. My lab sticks together and we take care of each other. The problem is a premed is used to volunteering for a semester at a time. Most of our first years as grad students we don't even figure out what the hell we're doing!
Well someone has to watch the baby. (and yes, that is what we call you in the most loving way.) You get different reactions to this duty depending on the person. I like it, but generally feel guilty because I can't give her hands on experience. Our lives (graduation) depend on producing good data, so it can be a while before anyone hands over experiments from their own research to you. We know you're smart, but we've already been in your shoes so we know that the virtue needed is more so patience or temperance. Our variability will go through the roof if we give you half the experiments. You just haven't had the 3 months of doing this 40 hours a week to get it where the scientific community places the bar. So you watch over the shoulder and do dishes. Other people get pissed because teaching you the basics takes away from their ability to do experiments. They feel like you'll never stick around to contribute to the lab, why bother?
The premed comes in and says "free work!" and is shocked when everyone turns back with hesitation and often anger. A doctoral student with a departmental fellowship is also free work with a higher education and the drive to produce.
Advice for making your best impression as a premed undergrad.
When you make an appointment to talk about research opportunities, know what they're researching. Then when you walk in, whip out your schedule for the next semester showing off big trails of free time. That means schedule your classes so you have at least one or two days with a block of 6 or more hours between 9 and 5. I could never teach our current undergrad how to run my experiment, it takes a total of 6 hours to complete if I'm on top of things. She only stays in the lab from 9 to 12:30 or so. You will seem endlessly more dedicated to the PI if you've already taken the time to fit work into your lab. That and promise of Summer work.
And if it really matters to you, tell them you're undecided about MD, MD/PhD, or PhD programs and you really want to put in an effort to get a better picture of it all.
In the end, it's not fair that they judge you by your predecessors. However, give them grumpy lab monkeys a break. They know more about what you're trying to get into than you do.
