scratchiness on older lp's

i recently purchased a 1950's set of lp's (ella sings gershwin) and while the records look beautiful for their age, not one visible scratch on any of the 5 records, when they are played there is a lot of scratchiness to them. they have been cleaned in a spin clean. i have only listened to three sides so far. i am wondering if i will be doing any damage to my needle by continuing to listen to this set.