Records not stored vertically for decades

@Soix - The records may be noisier and or skippy because the lower ones will have quite a bit of pressure on them so any surface contaminants are going to be well pressed into the grooves.

If 150 records is the totality of your collection, I would also carefully consider the opportunity cost of investing in a vinyl playback system versus what else you could do with your system.

lewm is right. If you have a friend with a decent analog rig, take some samples to him and give them a spin. Given the high cost of quality gear, it’s a good step.

A couple decades of records being stacked may actually help some warped LPs straighten out, in my non-informed opinion 

@lewm Raul’s Pontus are not valid or useful for my situation.  Did you not read my post?  I mentioned both the storage conditions and that I currently can’t play the albums, so I was simply asking what damage may have been done by storing the records flat in piles rather than upright/vertical.  That’s all.

@yoyoyaya Thanks for your thoughts regarding contaminants — that makes a lotta sense and makes me hope my better records are near the top 🤞🤞🤞.  Also, I already have a turntable/phono pre ready to go so won’t cost anything to get going but currently don’t have a place to set up my system due to personal circumstances.  Looking forward to rediscovering vinyl though.

@soix Here's my best guess as to what you may eventually encounter:

If the stacks were perfectly stacked one atop each other (i.e.  records and/or jackets not askew here & there) so that there was equal pressure on each disk and the floor was perfectly flat, the top 5 to 7 records of each stack might have some degree warping.  I don't think you have anything to worry about regarding groove damage.  The major concern, I believe, would be dust, mold spores or other fine infiltrates in the storage environment, especially if the records were not ensconced in and inserted properly into good quality anti-static inner and/or outer record sleeves.  If I were you, I would invest in a good record cleaning machine or system before playing those records on a good TT.  Depending upon how much you want to spend, there are a number of record cleaning options to consider (e.g.  ultrasonic, vacuum machines; manual cleaning; etc.).  Have a read (i.e.  not an easy read but worth the time) of this: Vinyl Record Manual Cleaning Process (thevinylpress.com)

Investing in a good TT is, obviously, also a must if you want good sound quality.  If you ultimately decide to go ultrasonic cleaning and don't want to spend 4K or more on a nifty ultrasonic cleaning machine, have a look at this: CleanerVinyl Ultrasonic Record Cleaning

Good Luck!